Everything that matters in South Malé Atoll happens underwater. Bring a mask: even the cheapest house reef will give you reef sharks and an octopus or two before lunch.
The most consistent diving is along the eastern channels — Embudhu Express, Cocoa Thila, Guraidhoo Kandu — drifts where the current carries you past the wall while sharks, jacks, and turtles work the edge of the blue. Kandooma Thila is the showstopper for advanced divers: a single submerged pinnacle ringed by reef sharks, eagle rays, and big schools of fusiliers. On the western side, the wall dives are gentler and good for less-experienced divers.
For non-divers, Maafushi is the practical base — a string of guesthouses, a bikini-permitted "tourist beach", and a steady supply of day trips out to sandbanks and snorkel sites.