Unisphere to Jones beach: 30 miles easy ride / 60 round. Total climb & descent respectively: 322 ft·335 ft out, and 315 ft·302 ft return. I'm biking back, but there is the LIRR that leaves Wantagh: 3:48pm for Jamaica/Forest Hills/Penn Station, 4:48pm to Forest Hills/Woodside/Penn Station
Helmet, tools to fix flat, spare tube, patch kit, LIRR bike permit(if taking train back), some cash, debit/credit card, ID if you want to get a beer(I suggest not while riding). It's also alway good to carry your ID, incase there's an emergency.
2-3 Banana, Hydration bottle/pack (may pick up on route if you decide to go light), beach blanket & towel, sun block