Muck dive sites are normally areas of wharves, marinas and tend to be at a more shallower depth, with black sand or perhaps sediment. Macro diving refers to the extreme close up you need to capture the details of some of these critters & can be in any situation or dive type. It is these muck diving destinations, like Lembeh Straits, Mabul & Kapalai, that offer weird and wonderful marine life.
Muck divers tend to be slow & patient underwater photographers, who are looking for rare nudibranchs, mantis shrimp, mimic octopus, juvenile fish, frogfish & small muck critters, like pygmy seahorses or ghost pipefish. Match this with a Macro Lens ( hence the name), the diver can get close and detailed.
Which means awesome underwater photography!