Kota Kinabalu offers a range of diving experiences such as wreck diving, wall diving, and macro life diving. Wreck diving allows divers to explore sunken World War II warships, while wall diving lets divers observe the stunning coral walls that drop off into the deep. Macro life diving gives divers the chance to see small and colorful marine life such as seahorses, nudibranch, and, in season, whale sharks.

The best time to go diving in Kota Kinabalu is from March to October when the weather is drier and the sea is calmer. This period also offers better visibility for diving. However, for those interested in catching a glimpse of whale sharks, the best time to visit is from April to May.

It is mandatory for all divers to have an Open Water Diver (OWD) certification or equivalent to participate in diving activities in Kota Kinabalu. Divers must also be in good health and have a proper understanding of diving techniques and safety procedures. Dive centers in Kota Kinabalu usually provide beginner courses, guided dives and refresher courses for certified divers.

When diving in Kota Kinabalu, divers can witness an impressive range of marine life from colorful coral gardens to enormous manta rays. Some of the underwater creatures that can be seen while diving include lionfish, barracudas, turtles, cuttlefish, and various species of sharks, including the elusive whale shark.

Kota Kinabalu has several popular dive sites, namely Tunku Abdul Rahman Marine Park, Pulau Tiga, Usukan Bay, Mayne Rock and Gaya Island. Tunku Abdul Rahman Marine Park is one of the most visited dive sites, offering a combination of shallow and deep dives, while Pulau Tiga is famous for its mud baths and crystal clear waters. Mayne Rock, on the other hand, is ideal for experienced divers as it offers sightings of big underwater pelagic species such as eagle rays and sharks.