Lets face it, only 10% of our oceans have been fully explored. Look at the Ceolcanth (probably spelt it wrong), thought extinct for millions of years until discovered I think in the late 1930+ by Malaysian fisherman alive, well and in enough numbers to sustain itself. Then look at Big Mouth, a type of large deep sea shark that layed undiscovered until it swallowed a ships anchor in the I think late 1980's. So who know's what's really out there when it comes to myths, as some are based on reality, only you don't if it's myth or real until one is caught or killed.