Killer whale
Information for offshore regions and warmer waters is more scarce, but widespread sightings indicate the killer whale can survive in most water temperatures. They have been sighted, though more infrequently, in the Mediterranean, the Arabian Sea, the Gulf of Mexico, and the Caribbean. Over 50 individual whales have been documented in the northern Indian Ocean, including two individuals that were sighted in the Persian Gulf in 2008 and off Sri Lanka in 2015. Those orcas may occasionally enter the Red Sea through the Gulf of Aden. The modern status of the species along coastal mainland China and its vicinity is unknown. Recorded sightings have been made from almost the entire shoreline. A wide-ranging population is likely to exist in the central Pacific, with some sightings off Hawaii. Distinct populations may also exist off the west coast of tropical Africa, and Papua New Guinea. In the Mediterranean, killer whales are considered "visitors", likely from the North Atlantic, and sightings become less frequent further east. However, a small year-round population is known to exist in the Strait of Gibraltar, mostly on the Atlantic side. Killer whales also appear to regularly occur off the Galápagos Islands.
Hainan
Hainan island has rich bio-diversity of cetaceans and is the site of studying these in Chinese waters. Many whales such as North Pacific right whales, western gray whales, humpback whales, and blue whales (all of these are almost extinct in Chinese waters) were historically seen in the winter and spring to mate and calve. These gentle giants of the sea had been hunted heavily and were wiped out by Japanese whalers (established whaling stations on various sites on Chinese and Korean coasts including Hainan and Daya Bay). A few Bryde's whales and minke whales may still occur in the adjacent waters along with on Leizhou Peninsula and the Gulf of Tonkin. Smaller species of whale and dolphins, such as short-finned pilot whales and pantropical spotted dolphins, but most notably the endangered Chinese white dolphin. Declared sanctuary for the species extends along the coasts. These dolphins may appear among clearer waters such as vicinity to Sanya.