Snorkeling and diving is good around the island.
The ship DISCOVERY is shipwrecked off Highborne Cay. I do not know the exact location of the wreck, but it was discovered by sports divers 1965 and was excavated by the Institute of Nautical Archeology in 1986.
R. C. Smith, et al., "The Highborn Cay Wreck: Further Exploration of a 16th-Century Bahamian Shipwreck," International Journal of Nautical Archaeology (1985). Reprint available
D.H. Keith, "Three Goals Set, Reached During Three Weeks at Hcay," INA Newsletter 14.3/4 (1988) 6-7.
T. J. Oertling, "The Highborn Cay Wreck: The 1986 Field Season," International Journal of Nautical Archaeology (1989).Reprint available
Equipment: Bring your own equipment. I don't think that there is any to rent.
Highborne Cay has the only marina in the northern Exumas. This is a small marina with 16 slips. As a visitor in the marina, you are able to walk around the island. There are electricity, water, fuel, laundry, b-b-q area, small grocery store, but it has no toilets or shore bathroom facilities other than an open air brackish shower. There is also no pumpout, and they don't want any discharge so boats have to go out and dump their holding tanks periodically. We bought fuel from them, and it is OK, but another boater bought fuel and his filters clogged up three times while he was getting it.
They will let you bring a dinghy in to the beach by the marina office, but boaters that are not at the marina are restricted from using most of the island and are charged for garbage disposal.
Equipment: It is also expensive – it has gone up to $1.50/$1.75/ft, water and up to 50 cents/gal for water. Laundry is $10/load (someone does it for you - it's not a self service thing). There is a 4% surcharge for credit card but they take (and would rather take) checks in US$.
There is a small store, and Janet of "Cool Runner" (which is the name of her boat) will bring food to the boat if you order dinner from her - call on the VHF.