Was able to get to Montauk on Saturday 5/13. Fishing was fantastic inside the park. Catch and release was especially productive, caught several large fish and a father and son pair were totally busting it up next to us on white maribou jigs. Lots of small escapees made fishing with most fly gear sort of annoying after the initial novelty wore off. I'd chosen to use a new Tenkara rod which made for some fun when I hooked on to some larger fish.
Was downstream near Van Tat for a bit. River looked good but was only able to spend 30 mins there. The parking lot is closed.
Campgrounds were full and the areas nearest the river looked like beach volleyball might be in order - sand everywhere.
Park looked good.