Non-photographers will find that they fill their slates with species long before the dive is over and the biggest problem for photographers is rationing their film. Mabul has several huge resident anglerfish, covered in algae growth. Muck divers have it particularly good on Mabul. Since most of the guests want to dive Sipadan, you may find you have a boat and guide all to yourself. The policy at Smart Divers Resort is that every divers gets to choose where they want to dive for the day and if only one person wants to dive around Mabul that day, then you end up with a boat all to yourself.
Limited numbers is probably a good idea anyway.
Most dive sites are either solid coral reefs sloping down to a silty bottom or a silty slope speckled with clumps of coral outgrowths. Visibility is never endless although it is usually at least 12 metres, but the silt gets kicked up easily which reduces visibility even more and makes photography difficult.