Wow... love it. I found a Casio divers watch in salt water and it was still running. I calculated by going backwards using the date indicated (assuming it was set at the date it was lost) it had been in the water for 3-4 years. The face had a few scratches on it, but it was still in good shape. Lets put it this way... it didn't look like that. Your find must have been there for quite a while. It is a real conversational piece.
Looks like someone had a meltdown... I dug an older tag out of the ocean a few years ago. Supposedly waterproof, but it has a little water under the crystal. May cost much to repair. In working condition it goes for around $700. Some suggest I just sell it as is for parts or let someone else gamble in getting it repaired. I placed it in a bowl of rice, hoping a good dryout will reveal little water damage in the inner works.