Aloha Rob,
Not sure if we've traded messages before and if I am duplicating I apologize. Lots of personal emails coming to me the last month and several here on the Scubaboard re:Niihau. I am a DM here for one of the local dive shops and CANT WAIT to start our tours over at Niihau/Lehua next month. Niihau is AWESOME. It is however an advanced trip and special considerations are appropriate. The best dives are sometimes a little deeper - and some of the better dives are drifts. IT IS CRITICAL for that reason that you have your weighting figured out before arrival at Niihau - which is why most companies suggest a local dive first. I "believe" that one of the other companies only does stationary dives due to the large amount of divers on the trip 16-20. Divers going on that charter can expect to have lines for their "ups and downs" as they will be stationary dives no matter what the current is doing. Any boat larger than a 6 pax is required to have a "bubble watcher" for safety if drifts are being done. Anyway, I do see people spend their first dive over there struggling to descend (or even unable to descend on the drifts) or popping to the surface without a safety stop. It's such amazing diving (and a once in a lifetime for most) so I hate to see someone go through that when it can be avoided. Be well rested for it - you'll be happy you were. It's a long day of amazing diving. Chances are you will see large schooling jacks, Endemic Lionfish(red), Monk Seals (Most endangered marine mammal in North America - yes moreso than the Manatee), whitetips and grey reef sharks, rare spotted knifejaws, rays of one species or another, schooling butterflys, and you may have a chance to snorkel with our Hawaiian spinner dolphins! Sounds pretty great? IT IS!
More info can be found through FATHOMFIVE.COM - 1-800-972