Pragmatically, to Shore dive on the Brac, you’re going to
need to get a rental car. Figure $200/week from B&S or
DDDD’s. You’ll also need to be on one of the hotel’s dive
packages, for they charge $8/tank if you’re not.
A quick map of where we're talking about
The two most commonly used public shore diving access points are Radar Reef and the "Buc" (the old Buccaneer hotel).
Radar Reef: Drive up to Stake Bay, turn left at the corner where the museum is. Go straight until you hit water...boat ramp dead ahead. There's a large diver-friendly staircase to the right side of the ramp. The ramp will be slippery... the stairs too, so check your ease of exit before everyone gets in. Also, since they built the breakwater here a few years ago, there's a lot of crud that builds up on the bottom here, so its very easy to kick it up and turn the viz to zero...can be intimidating for night dives.
Buccaneer: Drive to Tibbets Square and then make the turn towards the airport. After you pass the airport entrance (on your left), take the next street marked on the right. Its a dirt road. Perhaps 75 yards down this road, it "Y's" with one trail going straight and one going off to the right...stay straight. The road leads right down to the water and begins to bear right - - it loops around back to that Y. Park next to the large (recently enlarged) cut in the ironshore, gear up and check out your exit point before going in (ie, the boulders with the ropes in the corner). Straight out will be the #356 wreck, although its a loooong swim (20 minutes each way). You can stay closer in on patch/finger reef.
Boat ramps are another option. There's several. All will tend to be slimy/slippery:
On the north side: West End Not a boat ramp, but it does have water access. Go west (left) on the road towards the airport. Go past the airport turnoff, and the turnoff for the Bucaneer. Go past the public park. The road opens up into an abandoned parking lot area (the old airport terminal) and then makes a sharp right turn. Follow it and it immediately "T"s. Turn right at the T, then immediately left to find this road that leads right down to the water. This is a totally natural entry site with no improvements or clearing of rock/reef/rubble. BTW, this is also the trailhead for a real nice little coastal trail that runs from here through an ironshore area we call Grandma’s Toilet (just listen :-), up to the Buccaneer.
Also north side: West End, east of Tibbets Square. Go east (right) on the main road from Tibbets Square. As you pass Edd's Place (right behind Tibbets Square), turn left by the (Scott?) Construction company building. The road goes down to a breakwater that’s similar to the one at Radar. Ramp only; no staircase.
Northside - Duppy Reef - go to Radar, but turn left (west) and follow road down along coast. The second ironshore cut just before where the road turns left to run back out to the main road. This is a designated waterskiing area, so be careful here.
Northside - The Dock - officially, no scuba diving is allowed near the Dock, so you didn’t hear about this place from me. There's a nice miniwall drop-off here. Unobvious turn off; small, unimproved and unobvious water entry point. Recommended only with a local who knows how to do it (few do), which is why I won’t tell you if its on the east or west side of the docking facility.
Northside - "Handcuff" – a boat ramp, across from Spot Bay area police station. Unfortunately has a deserved reputation for underwater trash - considered to be Cayman Brac’s “worst” dive site in this regards.
On the Southside, conditions are generally unfavorable because its to windward, and the boat ramps are going to be unprotected.
Goat Head Bay (near the east cross-island road) from which the wreck of the Chester Pauling is nearby. Turnoff is within 20 yards of the cross-island road; I forget to which side.
Public Beach can be used as a shore entry, but it must be VERY calm in order to get over the shallow reef here. The tide makes a difference here.
Finally, the southside road ends in the West up at the ‘Westerly Ponds’, a nice place to watch sunsets from, BTW. There’s breaking waves here that are often used for surfing, so if you can make it out with a board, you should be able to dive or snorkel here as well...theoretically. But do watch for the currents, as they do tend to be present on the regular dive moorings here and if you get caught up, you will get swept out the point to the west...next stop, Little Cayman - - if you’re lucky.
At the hotels, they say that there’s not that much to see, behind the protected reef in Dick Sessenger’s Bay (the actual name of the protected anchorage). The water comes over the reef and then runs west and goes out the inlet. This current will sweep you out to sea if you get caught in it. Its progressively stronger the closer you are to the inlet. But there are some juveniles in here, as well as puffers, lobster and octopus, plus I’ve seen 3 types of rays (Sting, Butter & Eagle), tarpon, immature barracuda, Nurse sharks, baby Caribbean reef sharks, and God knows what else.