As for proximity to Waikiki, you might try diveoahu they are very close have their own boat, and good to dive with. Island divers is good, but they have this tendancy to pack people on their boat, and mostly dive out of the east side of the island. There are some good dives out that way don`t get me wrong, but every dive I`ve done out that way there has been current, and sometimes wavey conditions. One thing to make sure of no matter who you dive with here on Oahu, make sure whoever you dive with has their own boat. Diving with a company that rents seats on a boat isn`t that good. They tend to pack the boat, and rush you on and off the boat. By far the best operation I`ve dived with since I`ve been here is Captain Bruce`s! I can`t say enough good things about this boat, it`s a big boat big enough to easily get 20-30 people on, but he never puts more than 15 or 16 people on it so there is plenty of room to move around the boat, the boat has a warm water shower, and they always have food and beverage on the boat for you for between and after the dives. The only drawback to diving with him is the fact that he`s 45 min away from Waikiki, they do offer a Waikiki shuttle though so you don`t have to worry about the drive. He dives the Mahi shipwreck, and all of the other leeward coast spots. There is also shore diving as well. We have lots of good shorediving on this island, but I don`t recommend you go out trying to find it on your own. If you contact me off list I can put you in contact with a couple shorediving groups that won`t charge you to go out with us on a shoredive, you`ll just need to provide your own gear, and tanks. Hope this helps Scott