I snorkel the outside part of the jetty (the side facing AWAY from the inlet, towards the beach, and shielded from the tidal currents) all the time. It's an easy swim right off the beach, and drops off quickly to about 20-30 feet of water. Lots of hard corals on boulders on the deeper sections; some ledges; some rubble, etc on bottom. Depending on the season, barracuda, a few jacks and even occasional snook. Always parrotfish, blowfish, stonefish, schools of minnows and pinfish. Some caveats: its dangerous and illegal to swim on the inlet-side of the jetty; currents are very swift, the inlet is narrow, and there's a near-constant flow of yachts, cigarette boats, and day-boaters going through. Also, for max visibility, try to time your dive 3-4 hours after the incoming tide. That brings in fresh clear ocean water (visibility typically 20-30 feet) and leaves time for the tide to push back all the tea-colored water that comes out of the Intercostals Waterway on the outgoing tide.
From I-95, exit at Atlantic Blvd (Pompano Beach) and drive east all the way to the coastal beach highway, A1A (about 3-4 miles). Turn left (north) up A1A about 2 miles; just past the traffic light at 14th Street is a small public beach park (at 16th Street), with metered parking, bathrooms + outdoor shower. From there, it's about a quarter-mile walk along the beach to the Inlet (you can't miss it because the Hillsboro lighthouse is on the other side).