I'd love to know this as well - there's a chance (far from certain, but a chance) I'll be visiting a friend in Punta Gorda next year and if so I'll only be an hour's drive or so from Sanibel by my reckoning; would love to see wild horseshoe crabs.
They were spawning when we were there but, it's not hard to plan to be there when they are spawning because they spawn at the full moon in the spring and summer. The full moon is the best time to visit Sanibel because it also causes more extreme tides which makes some of the world's greatest shelling even better!! We were so lucky when shelling there that we found a rare junonia shell so we got our picture in the paper.
Shelling is where you go along the beaches finding different types of shells. Sanibel is considered one of the best places in the world to do this, everywhere you step on the beach is covered with shells.
