Additionally, water skis, wake boards, kayaks, jet skis, fishing, scuba, and snorkel equipment are available. This led to development of the modern diving mask, fins and snorkel. There are islands, villages, resorts to visit, snorkel and swim. They swim with only the snout above water, using it as a snorkel. When underwater, the elephant uses its trunk as a snorkel. Diving with snorkel is mentioned by Aristotle (4th century BC). No snorkel was fitted, due to difficulties in adapting the snorkel to the fleet boat. With their long snout and tubelike nostrils, these turtles can "snorkel" in shallow water. Submerged performance of the Fleet Snorkel boats was therefore significantly inferior to any GUPPY conversion. The tank can be equipped with a snorkel for deep fording. One can rent umbrellas, chairs, snorkel gear, and light refreshments. Modern radar is also capable of detecting a snorkel in calm sea conditions. The submarine could also run its diesel using a snorkel. "Diablo", one of the Fleet Snorkel boats, was converted immediately prior to transfer to Pakistan. Conventional diesel submarines must periodically resurface or run on snorkel to recharge their batteries.