Lembeh Strait

The Lembeh Strait runs between Sulawesi and Lembeh island near Bitung, and it is famous for exactly what most divers avoid: a bottom of black volcanic sand and silt with rubbish in it and almost no coral. That substrate turns out to be habitat for an extraordinary concentration of small, strange and highly camouflaged animals - hairy frogfish, mimic and wonderpus octopus, flamboyant cuttlefish, blue-ringed octopus, rhinopias, Bobbit worms, nudibranchs by the dozen - and the practice of diving slowly over sand looking for them, muck diving, was largely developed and named here. It is a photographers' destination above all, with resorts along the strait organised around that. Bitung is a working port, so the water carries traffic and the strait is not scenic above the surface.

What you actually see

• Black sand muck diving - the technique largely developed and named in this strait.
• Camouflaged rarities - frogfish, mimic octopus, rhinopias and flamboyant cuttlefish.
• A photographers' destination - the resorts and guides organised around macro work.
• A working port channel - shipping traffic and an unscenic surface.

When to go

All year; July to September for the clearest water. Four days.

Honest expectations

There is almost no coral and the visibility is often poor - this is not pretty reef diving. Rubbish on the bottom is normal. Blue-ringed octopus and other venomous animals are common; do not touch anything.

Nearby

Tangkoko is close; Bunaken and Manado are west.