After seeing such great responses, I felt obliged to tell some more.
Ancient wrecks:
Israel's location in the mediteranian sea puts it in a crossroads of ancient trade routes, both by land and by sea. The place here is actualy the connection between the 3 "old" continents- Europe, Asia and Africa.
I remember, when I was young, about 12 years old I went snorkeling a lot. It wasn't rare for me to find ancient relics- Anchors of different styles, from pre-historic ones (square stones with a hole in the upper part) to Napoleonic ones ("Admirality" anchors) and modern ones, "Greek fire", which is actualy a hand grenade of ancient days, Bronze nails and even once I found a medival sword!
most of these dives were just in a beach about half a kilometer from my house, that is not treated as a special archeology site. The ships I tolled about in my first message are located in a place that is a natural port. About 200 years ago Napoleon used it as his get-away point, after being defeated by the arabs. Finding muskets and cannons under-water there is not to rare. There are also the ancient ports of "Ceaseria" (the world's first open water large scale port, I belive) and "Ackers"(Akko in hebrew).
Ancient wrecks are not limited just to the mediteranean sea- In the Kinneret, just near Tiberias, an ancient 3000 years old, fishing boat was found a few years ago. It was coated with special material and taken out of the water for preservasion after a lot of hard work. The place also harbored, 2000 years ago a fleet that foght the romans in the small lake.
Modern wrecks-
I know of one War-world II wreck- An italian mini-sub that carried a detail of frog-man to mine the port of haifa. I belive it was shot by an english air-plane.
There are several ships that were sunk in purpose, to become diving sites. Several former Israely navy missile boats and a tow-boat. There are several merchant wrecks as well, the latest is a turkish ship, that sunk about 2 years ago near the coast of haifa.
What I'd really want to do, and didn't have the oportunity to do yet, is dive in the ocean islands, such as Bikiny or micronesia, and look for those BIG WWII battleships. A friend of mine dived in micronesia and toled me about what he saw there. Amazing.