Do you see a Sea Serpent or watery cryptid in this video at the 2:06 minute mark, moving in the lower right hand corner? Click to watch it full screen.

The black object that goes from apparently near the shore to the right hand corner is quite obvious. But as opposed to a creature swimming rapidly away from the shore, it probably is a bird flying over the water, away from the land and out to sea. Similar imagery has been recorded for Loch Ness, which at first looks like it is an animal in the water but upon closer examination is seen to be a bird over the water.

Due to the probable aerial nature of the object, even a bird is not necessary to explain the object. It, no doubt, is a helicopter or the shadow of a helicopter.