Not sure if you've already headed down here but if not I'd suggest snorkeling or diving the Blue Heron Bridge. It's a world-renowned snorkeling site because of the ease of access and variety of wildlife (seahorses, octopus, lots of different kinds of fish, baby sharks... lots of cool stuff!).
Here (zoomed out) you can see the bridge and Peanut Island just south of it. There are a couple of options to get from the bridge to the island. The island has really nice snorkeling on an incoming tide.
Here you can see a zoomed in shot of the charts there - there's some nice contour as it dips down away from the pilings:
It's definitely worth checking out!