Krov and Ann Menuhin, husband and wife film partners in underwater adventure swim with a 30-ton whale shark, 50 feet long and with a mouth five-feet wide - the largest fish in the world. In the Gulf of California they cruise and dive in one of the richest but least-known seas of the world. They meet huge gray whales, basking sharks, dive-bombing pelicans and the rare blue whale. They join the sea-lions' graceful ballet - and then encounter the gigantic whale shark.