Loch Ness Monster? Torpedo? US Navy installation? Apparently, this image captured by tourists off the Scottish coastline is a breaching basking shark (estimated at 3m in length!). More from Wikipedia:

• The basking shark is one of the largest known sharks, second only to the whale shark. The largest specimen accurately measured was trapped in a herring net in the Bay of Fundy, Canada in 1851. Its total length was 12.27 metres (40.3 ft), and it weighed an estimated 19 tons.
• The basking shark is a passive filter feeder, filtering zooplankton, small fish and invertebrates from up to 2,000 tons of water per hour.
• They feed at or close to the surface with their mouths wide open and gill rakers erect. They are slow-moving sharks (feeding at about 2 knots) and do not attempt to evade approaching boats (unlike great white sharks).
• As a result of rapidly declining numbers, the basking shark has been protected and trade in its products restricted in many countries. It is fully protected in the UK, Malta, Florida and US Gulf and Atlantic waters. Once considered a nuisance along the Canadian Pacific coast, basking sharks were the target of a government eradication program there from 1945 to 1970.

Second: any guesses as to how many fish in the image below? Divers estimated this shoal of sardines off a reef in the Phillipines to be 50ft wide, 50 ft deep, and over 400ft long (120m!). Best estimates are around 10 per cubic foot – around 350 fish per cubic meter)