It is locks with a tide gate,

not according to the United States Coast Guard, nor according the the United
States Army Corps of Engineers, but who are they to know?

jeffies, you have never seen the Shinnecock Canal, are never going to see the
Shinnecock Canal and most certainly are never going to transit the Shinnecock
Canal with your training wheels. Please don't bother to ever again comment on
this subject.

according to the Coast Pilot, Suffolk County
who owns
and operates it, and various people who have gone through it.