"Monster" photograph from English lake?

England's Lake Windermere is no Loch Ness, but two people kayaking on an office outing, think they saw a multi-humped monster. The story would end there except for the camera-phone picture you can see on the title link. A group of otters? A phenomenon caused by two wakes crossing? Could be either, but I'll grant them this appears more impressive than most "monster" photographs.

UPDATE: Well, yuck. A car tire turned up near the lake, slashed and stretched out so it could look like rubbery black humps.