Eastbound you can park at the boat launch area and walk back.
Westbound you can pull off the road and drive up to almost where the causeway ends and the bridge begins and walk south under the bridge.
You might want to take a few photos of the beautiful view before or after your search. If you are lucky you might see some dolphins swimming.
Be careful when climbing on rocks. Please replace the cache where you found it and do not give any hints, clues, etc. in your log/photos.