Rainy Day Things to do in Long Key, FL

We are heading down Thursday and the forcast calls for alot of rain (70%) as of now. I know there are not too many things to do IN Long Key but does anyone have any suggestions for the area....Islamorado, Marathon? We had planned to sun, swim, and visit the State Park but if it rains that much it may be a bust. So any rainy day suggestions would be appreciated!! Thank you in advance for your help!!