I spent some time every summer on Fire Island into my mid-teens. My Aunt and Uncle had a house there. Actually, they had two, a tradition house and then later they build the first pre-fab round house on the island.
What I remember most are my senses of the place. The painfully hot sand under my feet on the paved sidewalks. The salty scent to the air, even indoors. The cold of the water on the outdoor shower. The feeling that you can never escape the sand, it was in everything and everywhere. The thrill of riding on the ferry and the extra jolt of a thrill as we pulled up to the dock (knowing I was getting off for an adventure). The taste of the fresh grilled swordfish my Uncle would catch on his boat and we would eat on the breezeway at the wooden table long enough to fit my whole family.
If it will help, I can describe somewhat the places I used to go to there, though I can't remember any of the names anymore.