Passe en S

The Passe en S cuts through Mayotte's western barrier reef in a double bend that gives it its name, and the current running through it makes it the island's best dive: the walls are covered in soft coral and gorgonians, and turtles, reef sharks, eagle rays and large schooling fish work the channel. Humpback whales pass outside the pass in the southern winter. Mayotte's lagoon is among the largest enclosed lagoons in the world, and a dozen passes cut its barrier reef.

What you actually see

• The S-shaped channel - the double bend through the barrier reef.
• The coral walls - soft coral and gorgonians covering the sides.
• The pelagic traffic - sharks, rays and schooling fish in the current.
• The whale season - humpbacks passing outside from July to October.

When to go

May to October is the dry season with the best visibility; humpbacks pass July to October. The wet season brings runoff and poor visibility. Current governs when the pass can be dived.

Honest expectations

The current can be strong and this is not a beginner dive. Visibility varies considerably. Operators are few and booking ahead matters.

Nearby

Sada is east, and the lagoon runs north and south.