Conversation:

An interesting theory on the Loch Ness Monster is that there's a possibility that, like some animals, this creature can live in both sea water and fresh water, but it would prefer the sea because it has a larger supply for food. The loch is much calmer than the violent sea, so the loch serves as a breeding ground for the creature. It travles to the loch only to breed and then makes it's way back out to sea. This is why some expeditions to find the creature have been unsuccessful, it is not always there.

Here's what I've heard. Deep at the bottom of Loch Ness are a network of tunnels linking to other lakes, rivers & possibly to the sea. This might explain why no carcases can be found & how Nessie was probably able to escape from sonar. This might be the same for other lake monsters. Being able to escape from human detection might have given it (or them) time to reproduce without disturbance, which might explain the reason Nessie has been around for centuries. Or maybe she's just immortal?

Since Loch Ness is considerably higher than the sea, it's hard to imagine that it's linked by natural tunnels. Now, if the tunnels had valves or airlock-type double doors on them ....

TRiG.

They may not have to be linked to the sea, just connected underground.

Connected to what?

TRiG.

Underground water channels connected to each other. Either that or the creatures MAGICALLY TRANSPORT THEMSELVES to other dimensions.