Whales and dolphins in the Mediterranean Sea

Whales and dolphins in the Mediterranean Sea are a fascinating part of the region’s marine ecosystem. During my time in Sanremo, Italy, I joined a research excursion with the Tethys Institute to observe these impressive animals in their natural habitat. The warm and nutrient-rich waters of the Ligurian Sea attract several species throughout the year, making this area a great destination for marine wildlife watching. Experiencing whales and dolphins in the Mediterranean Sea offers unique insights into the region’s biodiversity and highlights the importance of preserving it. Read more about it in this blog post.

Mediterranean food. Mediterranean climate. Spain, Italy, Greece – I don’t know anyone who doesn’t like the Mediterranean. Whether it’s the cuisine, the warm weather, the laid-back lifestyle, or the sea with all the leisure activities it offers – there’s something there for everyone.

Speaking of the sea: During my stay in Sanremo, in the northwest of Italy, I realized how little I actually knew about the Mediterranean Sea. It’s not far from Germany, where I live. I had already been to its shores in Spain and Greece. And the internet is overflowing with information about this vast body of water. But still, I had to admit: I knew surprisingly little about the Mediterranean Sea and the wildlife that calls it home.

Probably the most fascinating thing I learned was about the narrow strait that connects the Mediterranean Sea to the Atlantic Ocean – and just how essential it is for the sea’s survival. Without this connection – that is, without the net inflow of water from the Atlantic through the Strait of Gibraltar – the Mediterranean would lose so much water through evaporation that its sea level would drop by about one meter per year. Over time, this would cause the sea to largely dry out within a few thousand years.

Apparently, if the Strait of Gibraltar were closed, the Mediterranean’s sea level would decrease by roughly one meter per year due to the imbalance between high evaporation and relatively low precipitation and river inflow.

The water entering the Mediterranean through the Strait of Gibraltar is cooler and less salty than the water already in the sea. As it circulates eastward, it gradually warms up and increases in salinity. This denser water then sinks, especially in the eastern Mediterranean, and begins to move westward at deeper levels, eventually exiting the sea through the same strait.

This is, of course, a simplified description of the complex water circulation system in the Mediterranean. But in general terms, it’s accurate to say that evaporation in the Mediterranean far exceeds precipitation and river inflow – which is why the inflow from the Atlantic is essential.

As for tides, they are relatively limited in the Mediterranean Sea due to the narrow connection with the Atlantic. Nevertheless, tidal forces still play a role in driving the water exchange between the two bodies of water.

The most alarming fact I discovered about the Mediterranean Sea is how significantly it has warmed in recent years. Data from the Copernicus Marine Service show that June 2025 was the warmest June ever recorded in the region, with an average sea surface temperature of 23.86°C. Moreover, 62% of the Mediterranean’s surface experienced marine heatwaves of strong or greater intensity.

A report from the European Environment Agency reveals that European seas—including the Mediterranean—have warmed significantly since 1870, with recent years ranking among the hottest on record. Under high-emission scenarios, sea surface temperatures are expected to rise by an additional 2 to 6°C by 2100, resulting in more frequent and intense marine heatwaves.

Statista features a chart displaying surface temperature anomalies of the Mediterranean Sea from 1994 to 2023, clearly illustrating the upward trend in sea surface temperatures over this period.

This is deeply concerning — not just for the incredible marine life of the Mediterranean Sea, but for all of us on this planet.

Before diving into the main topic of this blog post — whales and dolphins in the Mediterranean Sea — let’s take a moment to appreciate some key facts about this unique sea.

The Mediterranean Sea covers an area of approximately 2,500,000 km², making up about 0.7% of the world’s ocean surface.

That might seem like a small fraction, but for a semi-enclosed sea, it's truly remarkable — both in size and in ecological importance.

The Mediterranean Sea stretches approximately 4,000 kilometres from west to east, spanning from the Strait of Gibraltar to the Gulf of Iskenderun in southeastern Turkey. From north to south, its widest point—from the southern coast of Croatia to the shores of Libya—measures about 800 kilometres. To put that into perspective, that's roughly the distance from London to Cairo.

In the northeast, the Mediterranean Sea is connected to the Black Sea through the Bosporus Strait, and in the southeast, it links to the Red Sea via the Suez Canal.

When I travelled to Italy in the summer of 2023 to observe whales and dolphins in the Mediterranean Sea, I stopped in Sanremo, located along the Ligurian Sea.

There are many places where you can observe whales and dolphins in the Mediterranean Sea. So, why did I choose Sanremo?

Well, I decided on Sanremo because it's home to the Tethys Research Institute, a non-profit organization dedicated to the study and conservation of whales and dolphins in the Mediterranean Sea. What makes Tethys especially interesting is that it not only conducts scientific research, but also offers multi-day boat expeditions where participants can actively take part in fieldwork.

You don’t need to be a marine biologist, a student, or a specialist to join. Anyone with an interest in whales and dolphins in the Mediterranean Sea can take part, learn from experienced researchers, and gain first-hand insight into how marine scientists study large marine mammals at sea (left: bottlenose dolphins, right: sperm whale).

Just a quick note: Before heading to Sanremo to observe whales and dolphins in the Mediterranean Sea, I made a short stop in Nice (France) and also visited the Oceanographic Museum in Monaco. If you're interested in these two places, feel free to check out my previous blog post!

The study area of the Tethys Research Institute lies within the Pelagos Sanctuary for Mediterranean Marine Mammals — a vast marine protected area dedicated to species such as whales and dolphins in the Mediterranean Sea. It has also been officially designated a Specially Protected Area of Mediterranean Importance (SPAMI).

Covering an area of approximately 84,000 km², the sanctuary is located in the northwestern Mediterranean Sea, stretching between Italy, France, and the island of Sardinia, and encompassing Corsica and the Tuscan Archipelago.

Established in 1999 through an agreement between Italy, France, and the Principality of Monaco, the Pelagos Sanctuary is, to the best of my knowledge, the first — and currently still the only — international high seas protected area in the world.

The Pelagos Sanctuary is home to eight cetacean species:

Fin whale (Balaenoptera physalus)
Sperm whale (Physeter macrocephalus)
Cuvier’s beaked whale (Ziphius cavirostris)
Long-finned pilot whale (Globicephala melas)
Risso’s dolphin (Grampus griseus)
Bottlenose dolphin (Tursiops truncatus)
Common dolphin (Delphinus delphis)
Striped dolphin (Stenella coeruleoalba)

Well, from all of these eight species, I have already seen five species.

I have seen common dolphins in the Azores (photo on the left) and in South Africa (photo on the right).

When we spotted the bottlenose dolphins, excitement quickly spread across the boat. Researchers and interns rushed to gather as much data as possible while the animals lingered at the surface.

At the Tethys Institute, one of the key methods used is photo-identification: by photographing the dolphins’ dorsal fins, researchers can recognize individual animals. This technique provides valuable insights into their distribution, social structures, and seasonal presence.

I also tried my hand at photographing the dolphins’ dorsal fins — which turned out to be quite a challenge! Afterwards, I was happy to share my pictures and contribute them to the ongoing research.

Although the Mediterranean Sea is home to many species of whales and dolphins, on that day we “only” saw bottlenose dolphins. The group we encountered was relatively small. Interestingly, some bottlenose dolphin groups can number up to 1,000 individuals (see Whales, Dolphins, and Seals – A Field Guide to the Marine Mammals of the World) — an impressive sight, though I have yet to witness anything of that scale myself.

The dolphins we observed seemed quite focused on feeding, so they probably paid little attention to our presence.

The next day, we were lucky enough to set out from the port once again. The researchers had already warned us that strong winds might keep us in port the following day, so I was determined to make the most of this second chance on the water. I felt genuinely excited and grateful that we could head out once more in search of dolphins — knowing that the weather could easily have put an end to our plans.

As we left the shore behind, the sea greeted us gently, and it didn’t take long before we spotted movement in the waves. Soon, a group of dolphins appeared, gracefully breaking through the surface. Once again, they were bottlenose dolphins, and watching them glide through the water felt just as magical as the first time.

One of the dolphins had a striking white patch on its dorsal fin, while the others had grey fins that were far less distinctive — though some bore tiny markings that are hard to spot from a moving boat, especially for untrained eyes like mine. Out on the water, the most important task is to gather as much data and as many photos as possible. The real close-up work happens later, back at the desk.

Then, suddenly, a dolphin with a truly distinctive dorsal fin surfaced, instantly catching everyone’s attention.

I was also trying to photograph the dolphin from the other side — not an easy task at all. It depends heavily on the boat's position and the direction in which the dolphins are moving. Fortunately, the researcher on board communicated closely with the skipper, which really helped. In the end, I managed to capture an image of the dolphin with the distinctive dorsal fin from the other side, and I also got a shot of the dorsal fin of the dolphin with the whitish patch. However, I’m not sure whether any of these photos are actually useful for research, given the angle. But well — I did my best.

What seems to capture everyone’s attention, however, is when a young dolphin swims alongside its mother. And honestly, I found it just as thrilling — and deeply moving. In this case, the calf was already a bit older, no longer a newborn, but still clearly staying close to its mother. I was lucky enough to capture a few photographs of the pair swimming together in perfect sync. Moments like these are a beautiful reminder of the strong bonds within dolphin families — and of how special it is to witness them in the wild.

A study on bottlenose dolphins found that calves are typically weaned by around three years of age, although exceptions do occur — with one individual in the study being weaned as late as its fifth year. However, even after weaning, when the mother no longer lactates, a strong social bond between mother and calf often remains. These post-weaning associations can last anywhere from four to ten years, meaning the calf continues to stay within the maternal group. It is important to note, however, that these observations are based on a relatively small sample of just nine calves.

Thanks to my fast camera, just a millisecond later I captured a photo that showed the face of the second dolphin very clearly. By the way, this was the dolphin with the distinctive white patches on its dorsal fin. It was truly amazing—not only to see the dorsal fins, which are often the main focus, but now to get a clear glimpse of the dolphin’s face, revealing more of its character and expression. Moments like these make the experience unforgettable and deepen the connection to these incredible animals.

As we headed back out to sea, I was secretly hoping to spot a sperm whale. The researchers from the Tethys Institute use a special acoustic device to detect them underwater. Unfortunately, there were no vocalizations — nothing to indicate the presence of a sperm whale. Normally, as soon as a sound is picked up, the boat would change course and head directly toward it.

But with no sounds detected, all we could do was continue searching, slowly moving across the open water.

Then suddenly, a sound came through the device — not a sperm whale, but dolphins!

The boat quickly changed direction, following the signal.

Could it be bottlenose dolphins again?

No — this time, it was a group of striped dolphins that appeared at the surface.

At first, there appeared to be only a few dolphins, and I was only able to capture glimpses — a tail here, the curve of a back there, or often just a splash. They were moving incredibly fast. But soon it became clear that the group was much larger.

Striped dolphins are known to be highly social animals. They typically travel in groups of 20 to 50 individuals, though sometimes in the hundreds (see Whales, Dolphins, and Seals – A Field Guide to the Marine Mammals of the World).

When so many dolphins are moving that quickly, photo-identification seems almost impossible. Still, I did my best to capture at least a few usable images.

At one moment, I managed to capture the face of a dolphin — though part of the ship’s rail ended up in the frame as well.

But in the photo above, you can clearly see its beautiful coloration — the striking contrast of light and dark tones along the body. Especially noticeable is the prominent black stripe running from the eye down to the anus, a characteristic feature of striped dolphins (but not fully seen in the photograph).

Nevertheless, I shifted my focus to the dolphins a little farther away, hoping to capture clearer photographs. Suddenly, to my delight, a dolphin leapt out of the water, almost balancing vertically on the surface. It was truly a breathtaking moment.

As mentioned earlier, the weather forecast for the following day didn’t look promising — and in fact, we had to stay in the port for two full days.

During the five days with the Tethys Institute, we all lived on the boat. The night from the second to the third day was especially windy — something I both heard and felt while lying in my bunk. So in the end, I was actually relieved that we didn’t go out to sea that day.

On the third and fourth day, the strong wind was still clearly noticeable, especially from a scenic viewpoint in Sanremo. You can see some photos from that location further down in this blog post.

Fortunately, on the fifth day, the weather finally turned — the sky was bright, the sea calm, and we were able to leave the port again. From afar, we could already see another boat out on the water. Some gulls seemed to greet us as we set off. The conditions were perfect — and hopes were high.

Let me say it right from the start: we didn’t see any bottlenose dolphins this time — nor any striped dolphins. But instead, we were lucky enough to encounter a solitary male sperm whale.

It all began when the researcher on board picked up the whale’s vocalizations using the acoustic device. The skipper immediately set course in the direction of the sound. Then we waited.

It didn’t take long — soon we heard the unmistakable blow, and moments later, we saw the first spout rising from the surface.

By the way, in sperm whales, males are roughly twice as long as females — a truly remarkable difference. In biology, this is known as sexual dimorphism, where males and females of a species differ significantly in size or appearance.

At first, I must admit, I thought there were two sperm whales at the surface. But that wasn’t the case. What I mistook for a second animal was actually the large snout and the hump of a single whale, both protruding clearly above the water. It’s easy to be fooled for a moment — especially when seeing such a massive animal in the open sea.

Information: Happywhale is a great platform for sharing photographs of whale tail flukes. By uploading a photo, you can find out where a whale has been seen before — and whether it has been recorded elsewhere. In this case, the sperm whale I photographed hadn’t been matched with any previous sightings. Either no one else has seen this individual yet, or it simply hasn’t been submitted to Happywhale. So for now, I wasn’t able to learn more about this particular whale — but who knows what future matches might reveal!

After the sperm whale disappeared into the depths, we began preparing lunch. It was actually the first time during those five days on the boat that we had lunch out at sea instead of back in the port.

Returning to land would have taken too much time — and since all the food was already on board, there was really no reason to go back.

So we stayed out on the water, enjoying the calm and the sunshine, and waited in hopes that the sperm whale might resurface.

It truly was a beautiful day — peaceful, memorable, and filled with quiet moments of wonder.

It was the second — and also the last — time we saw this sperm whale. We waited a while longer, hoping it might surface again, but it had apparently moved on.

So we left the area and continued our search for other sperm whales or perhaps even different species.
Unfortunately, we weren’t lucky that afternoon. We spent several more hours out on the boat, scanning the sea, but no more marine mammals appeared. At one point, some striped dolphins were heard acoustically, but we never caught sight of them.

Still, as we cruised along the coast, the stunning views of the shoreline and the vast, open sea more than made up for the quiet spell. Sometimes, it's not only about what you see — but also about being present in that moment, surrounded by nature.

The Tethys Institute, from where the excursions departed, is located in Sanremo — a charming coastal town in the northwest of Italy, just about 20 kilometers from the French border.

Sanremo is not only a great place for watching whales and dolphins in the Mediterranean Sea, it has both a picturesque Old Town and more modern districts. I was especially taken with the Old Town, which climbs steeply up the hillside. It’s a bit of a workout, but absolutely worth every step. One of the most fascinating places there is the passage called La Pigna — a maze of narrow alleys, arches, and stairs that feels like stepping back in time.

One evening, on a day we didn’t go out to sea, we sat there enjoying the warm summer air and the lively atmosphere. Music filled the streets, and yes — it was quite crowded, but in a cheerful and relaxed way. Sanremo is a lively, friendly town that welcomes you warmly.

I have to admit, I didn’t really dive into the town’s history. But one afternoon, I visited an exhibition about Frida Kahlo. Admittedly, this doesn't have much to do with Sanremo or Italy — but it just goes to show that there’s culture here, too, if you’re looking for it.

Since this blog post is primarily about whales and dolphins in the Mediterranean Sea, I won’t go into too much detail about Sanremo — but I’d love to share a few visual impressions of the town with you below.