There's a surprising amount to do here, including fishing, spotting wildlife from kayaks at Deal Lake, or even surfing. AP has a new bikeshare service and most communities can rent you wheels. And, of course, there's miles of boardwalk to meander at your own pace, and historic lighthouses to climb.
Many communities on the Jersey Shore charge $5 to $9 for access, issuing a badge (also called a tag) for the day. From Long Beach Island north to near Sandy Hook, all beaches have a fee; the southern Shore is mostly, but not entirely, free. If you're staying a few days, it's worthwhile investing in a weekly badge, although some hotels provide them.