It depends. If you want to get the pavilion that is there then yes, you must reserve it in advance. There are a few other parts that require permits. The rest of the park is first come first serve.
I suggest you to stay away from this park. The picnic area has no water to wash anything neither it has a water fountain to drink water. The fishing pier is coming apart. The boards are loose and has caused couple of people to fall. Even though it has been reported nothing has been done by the park employees and the man in charge. Third world countries have better parks than this. It is shame that the town of North Hempatead supervisor has let this most beautiful place go to pieces.
Thanks! Your answer is awaiting moderation.