Here is a short excerpt from a trip report I posted on another board several years ago after visiting this region for a couple weeks. I too have since been diving all over the Caribbean and have found nothing to equal the experiences of Saba.
"But now for the best part ..... SABA. This is diving of the highest order. I'm sure it can compete with any diving on the world. Saba is a small volcanically formed island (about 5 miles in diameter) with 1,000' walls dropping straight into the ocean. Peaks on the island reach 3,000' with rain forest everywhere. I am describing this to assist in visualizing that this same terrain exists underwater around the island. A typical dive site has a mooring buoy located on a pinnacle at 85' to 100' beneath the surface. Visibility is usually over 100', so the pinnacle is immediately visible when you enter the water. From there, the dive may be over the pinnacle top, if broad enough, and becomes a reef dive. Or, it may be swimming through blue water to another pinnacle top or wall several hundred feet away.
One site called 3rd Encounter has three mooring buoys within about 500' of each other. I truly believe one could spend a week diving this site and never repeat the same dive! By way of example, the Eye Of The Needle is a dive which begins by dropping to a pinnacle at 95', then swimming due west through blue water with 200' below and 100' above for about 100 yards.
Suddenly you realize a structure is appearing in the distance out of the blue haze. It looks sort of like a pillar. As you approach, the brilliant colors of the coral start appearing and you realize this is a formation about 40' in diameter which begins about 100' below (you can see the bottom) and extends about 40' above you to within 60' of the surface. You drop to 130' or so, and begin a wall dive slowly ascending as you circle the formation like a barber pole. Small fish surround the coral everywhere, caterpillar-like creatures crawl the surface, all the coral is totally alive and brilliantly colored, several black-tip sharks cruise in the distance, and larger fish like jacks and yellow tails are suspended like ornaments everywhere. I just wished I could hang in one spot forever and watch the show before me. If this ain't diving, I don't know what is! "