One Ocean is the oldest and most reputable dive operator in Tanzania, diving in Zanzibar since 1993 and the island's first PADI 5 Star Dive Centre. It runs dive centres and booking offices in Kendwa, Matemwe/Kiwengwa and historic Stone Town, giving access to Tumbatu Island and Nungwi Reef in the north-west, the Mnemba Atoll from the east coast, and coral gardens, wrecks and night dives found only around Stone Town on the west coast. Dive groups are capped at 6 people per dive leader, all boats carry safety gear including oxygen, first aid kits and a second engine, and the centre is a DAN Safety Partner with staff trained as hyperbaric chamber operators. One Ocean offers the full range of PADI courses from Bubblemaker and Discover Scuba Diving through Divemaster, daily fun diving and snorkeling trips, night dives, and extras such as sunset dhow cruises and a Prison Island snorkeling excursion from Stone Town, with free transfers around Matemwe and Kiwengwa.