Certification: divers have to be certified by a professional organisation like PADIor BSAC. Divers are awarded a log book and C-card as proof. They need to produce these to be able to dive.
Drift diving: currents carry divers over reefs.
Liveaboards: diving cruise for experienced divers.
Shore dives: divers walk into the sea from the beach.
Two-tank dive: two separate dives from a boat. Divers take short breaks in between but do not return to shore.
Wall dives: divers descend from a boat to explore underwater cliffs.