Cryptozoology

Originally Posted by eriol

I've been thinking about this as well. Why dont they just enter the lake with some kind of submarine and do a full investigation? Anyone could explain the reason behind this? Has there been any project like this actually?

They have used sonar in the Loch. However, it is a very ineffective method considering the structure of the lake. There are many caves, undercuts, and ledges which give the possibility for the Loch Ness monster to hide while they are performing a search. Because of this possibility, they cannot rule out that they might have simply missed the creature because it is hiding.
One time, they caught on sonar what appeared to be the the flipper of the beast, but later found out that it was nothing but a flipper-shaped outcropping.

Jam it back in, in the dark.