Just Below the Surface with Nils Bertrand

With its turquoise waters and incredible biodiversity, Mayotte’s lagoon is one of the most pristine in the world. Nils Bertrand, head of Seablue Safari, has been exploring these waters for 25 years. He shares the unique experience of his sea excursions with us.

• NGT: Hello Nils, can you tell us about the Seablue Safari experience?
• Nils Bertrand: The Seablue experience is 25 years of passion for Mayotte’s lagoon, its unique marine ecosystem, and the extraordinary encounters it offers. Here, every excursion is an immersion into a still-preserved world, where nature reigns supreme. My goal is to bring visitors as close as possible to this exceptional wildlife while adopting an environmentally respectful approach.

What Can You Expect to See on a Seablue Safari Excursion?

One of Mayotte’s greatest assets is its incredible marine diversity. Whether snorkeling or simply observing from the boat, you’ll witness a true mosaic of species.
The coral reefs are teeming with life, forming a vibrant ecosystem. Sea turtles are everywhere, offering magical moments as they peacefully graze on seagrass beds.
Then, there are the dolphins—several resident species inhabit these waters, including Indo-Pacific bottlenose dolphins (Tursiops aduncus), spinner dolphins (Stenella longirostris), spotted dolphins, short-finned pilot whales, and even the rare humpback dolphins (Sousa plumbea).

Whale season, from July to October, is a highlight. You can witness fascinating behaviors, such as male escort displays, tender interactions between mothers and calves, and young whales exploring their environment.
From February to June, majestic manta rays take center stage. With just a mask and snorkel, you can watch them gracefully spiral above the reefs.
For thrill-seekers, we also offer special shark excursions, allowing you to observe these fascinating predators in their natural habitat.
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And occasionally, we’re lucky enough to encounter truly exceptional visitors—orca, sperm whales, and even dugongs… Here, anything is possible!

What Has Been Your Most Memorable Encounter at Sea?

Without hesitation, the orcas in 2015. During peak whale season, a group of about fifteen orcas entered the lagoon to hunt. The spectacle lasted for more than three weeks—an absolutely timeless moment. We were able to witness their intelligence, their hunting strategies, and even incredible interactions with other species.

​A memory etched forever!

A Full Immersion into Mayotte’s Lagoon

Can you tell us about the different experiences offered by Seablue Safari?

• Nils Bertrand: Our excursions are full-day expeditions. We don’t offer short boat trips of just a few hours because truly exploring Mayotte’s lagoon takes time. Each outing is an adventure—an immersion into one of the richest ecosystems of the Indian Ocean.

All year round, we set out in search of dolphins. They are ever-present and offer magical encounters. We also explore the coral reefs, perfect for snorkeling, and make stops on pristine white sand islets, the true gems of the lagoon.
Certain times of the year offer unique experiences:

• From March to June, it's manta ray season. With just a mask and snorkel, you can watch them glide through the water with mesmerizing grace.
• From July to October, humpback whales take center stage—an awe-inspiring spectacle that never fails to amaze.
• We also organize sunrise excursions, where we navigate through the tranquil early morning atmosphere. This is a special time to observe wildlife in the peacefulness of dawn.

For those looking to explore the full diversity of the lagoon, we offer complete island tours. This circuit takes visitors to must-see sites such as the mangroves, Soulou waterfall, the iconic "S Pass," and the white sand islets. These excursions are less focused on wildlife encounters but provide a broader perspective on Mayotte’s history and landscapes.

And for thrill-seekers, we have created the Big Fish Out expeditions—a quest for sharks, without scuba tanks, only snorkeling. We search for reef sharks, bull sharks, and even tiger sharks. It’s an adrenaline-packed experience, always conducted with the utmost respect and safety.

A Lagoon in Danger?

How do you see the evolution of the lagoon since your arrival? Is it in danger?

• Nils Bertrand: Yes, clearly, Mayotte’s lagoon is facing many challenges. I’ve seen its waters change over 25 years of exploration. Some reefs are suffering from climate change, human pressure, and pollution. Growing urbanization and uncontrolled development pose real threats.

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But it’s not all lost. There are still incredibly well-preserved areas, and we’re lucky to have one of the world’s richest lagoons in terms of biodiversity. We must act quickly, raise awareness, and encourage a more respectful approach to tourism. At Seablue Safari, we try to contribute by educating our visitors and minimizing our impact.
Mayotte still has so much to offer, but its beauty is fragile. It’s up to all of us to take care of it.

A Changing Lagoon, A Fragile Balance

NGT: You’ve been observing Mayotte’s lagoon for over 20 years. Have you noticed any changes in the underwater fauna?

Nils Bertrand: Yes, and unfortunately, the difference is striking. Twenty years ago, we used to see many more large fish, particularly the Napoleon wrasse, which used to populate the S Pass in large numbers. Today, their presence has become much rarer.

The main cause? Excessive fishing pressure. Some iconic fish, which were once an integral part of our excursions, are now harder to observe. Fortunately, Mayotte remains a relatively preserved sanctuary. Compared to other lagoons in the Indian Ocean, our human impact is still limited. We have vast areas where nature is still thriving, but it’s crucial that we ensure we don’t cross a critical threshold.

From a Childhood Passion to a Marine Vocation

NGT: Can you tell us about your journey? How did you end up in Mayotte?

Nils Bertrand: My love for the sea comes from my father, a passionate sailor. With my brothers, who are an integral part of the Seablue team, we grew up on the water. My father even built us an Optimist, our first boat. This passion gradually became a bigger part of my life. However, at first, nothing indicated that I would turn it into a profession. I eventually trained to become a sailing instructor, before specializing as a skipper and yacht delivery captain.

It was this path that led me to the Indian Ocean. When I discovered Mayotte and its lagoon, it was a revelation. I was fascinated by the tropical marine world, and especially by marine mammals: dolphins, whales… From that moment, sailing became a means of exploration, rather than an end in itself.
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I realized that what truly captivated me was the encounter with wildlife, the connection with these animals in their natural habitat. That’s how Seablue Safari was born—an adventure driven by curiosity, respect, and the desire to share this passion.