The Salt Pier -- which no longer requires harbourmaster permission -- is a shore dive site, a short drive south of the airport. You still need to check for a salt ship: when a ship is being loaded with salt, no diving is permitted.
But when there is no ship, just drive a little bit south of the pier itself, park your truck just past the small building, and you're ready to walk into the water on a rubbly but fairly calm beach entry. If you look, you can also see crabs and snails on the rocks -- and often herons in the narrow channel across the road, next to the salt pools.
For the dive, once you're in the water, it's less than 200m (600') of surface swimming to the end of the pier. Drop down, and you'll be stunned by the amount of coral and sponges that have taken up residence on the pier pilings, and the hundreds and hundreds of fish that have made it home.
Apart from the usual reef fish (and a lot of them!) we saw morays, squid, barracudas, three (!) spotted drums and juvenile angelfish. The best spots to see things are the pilings themselves, the coral rubble and man-made junk, especially near the central pier, and the shallower parts near those pilings.
It's not a pristine reef, but neither is a wreck dive, and the amount of sea life on this site was excellent, and it's an easy enough dive even for beginners. There were lots of photo opportunities, too, so we went back and dove it a second time in our week on Bonaire.
Start with the surface swim and finish with a dive through the shallows to the shore, and you can enjoy an outstanding hour or so under water.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.