M60 tanks undergo a thorough cleaning before use as reefs
The Artificial Reef Program used four types of obsolete Army armored vehicles as artificial reef materials off the New Jersey coast. These were cleaned at local military bases, loaded onto barges for transport, and pushed off at their final destination. Once the Army had disposed of its excess inventory, the program ceased, around 1999. The Artificial Reef Program has sunk almost 400 tanks altogether, far too many to list them here in this website.
There are two actual Ponquoque bridges, the new one and the old one. You crossed the new bridge to get to the former Foster Road. The old bridge is where you will probably dive, although nothing is stopping you from diving the new bridge. Don't get caught in the channel between the two bridges, however, because it is considered a channel and it is illegal to dive in a channel in the town of Southampton. With that in mind, there is usually good parking at the bridge, but you will have to do some walking in order to get into the water.