The salt water part is not particularly surprising to me, after all we have plenty of wooden shipwrecks from the bronze age. Wood is preserved much better in the salt water than on the ground (unless it's a desert).

What I don't understand is how it survived the surf. 2 meters per century means that the place had spent a century in the surf line, and surf grinds everything into sand and dust and scatters what it can't grind. I would have understood a sudden flooding but this is surprising.