1) Now I keep reading how it's one of the best, if not the best dives in the Hawaiian islands and a few people saying it is amazing and can't miss dive. But I've also read a couple of trip reports of people saying it was a great dive but very over hyped and that it may well be one of the best dives you can do in Hawaii but that's not saying much because diving in Hawaii is nice but nothing to write home about. Soooo.. which is it?
2) And with regards to Kauai diving, which is better, south side in the winter (Sheraton Caverns, Koloa Landing) or north side in the summer (Tunnels Reef)?
3) And finally has anyone done Lanai Cathedrals from Mauai? How does it compare to the topography dives around Kauai? Thanks!
Here are some thoughts on these three areas:
1) "Diving Niihau" is almost never actually diving at Niihau, a private island. Instead, the trips take you to Lehua, a crescent shaped volcanic islet near Niihau. Whether it is all it is hyped up to be is always a matter of opinion, preference, conditions, cast of the day, etc. Trips to Lehua are canceled more frequently than the average dive trip based on the distance to travel and exposure to open ocean conditions in the middle of the Pacific. On one trip I tried 4 times-got skunked. When conditions allow the trip, some folks are put off by the frequently challenging boat crossing (worst on the way back). Once there, the visibility averages 80' to 100' or more but can be down to 30' at times. The sheer drop offs and larger life such as sharks, monk seals, mantas and ocassional whale sightings in winter can be absolutely spectacular, fish variety is very good, other vertibrates and invertibrates as variable as anywhere. Most days the diving there would be considered intermediate to advanced and divers should be equipped with all prudent safety tools ie knife, light, auditory signalling device, inflatable surface marker, signal mirror, and perhaps a nautilus gps locator/radio. Getting lost isn't planned/expected/ or common but with the remoteness of the site without these tools... well, you get the idea.
2) Tunnels is renowned for the unique topography and turtles. The arches and swim throughs are interesting ( though almost devoid of coral) and the fish life is sometimes abundant. The coral is less abundent-significantly less abundant than the South shore. South shore areas have more coral than the Tunnels dives, they also have turtles, rays, abundant fish and invertibrates. Either South or North can be made undiveable by seasonal swells. Swells can wrap the island and effect all shores sometimes. Keep in mind, North shores on Kauai get rain most days for part of the day, usually more overnight but morning and afternoon showers are common. South shore areas would be desert like without the irrigation of development meaning it is almost constant sun.
3) Lanai Cathedrals is two seperate dives. Usually you will get one or the other depending on other boats present, prevailing conditions, captains choice. The 2nd dive will usually be elsewhere on Lanai. The topography and contour is quite unique and interesting. You must be comfortable entering a space with very limited exits. You will be guided but will enjoy it more if you bring your own bright light as well. You can light up the chimneys where the lobsters, eels, crabs, corals, etc are in dark spaces. Once outside of the "cathedral" you will have a reef to explore with more color. Second sight dives at Lanai are often more "fishy" than almost any other dive with the exception of Lehua. The limited development of Lanai and slightly less traffic in the ocean in general keep many of the reefs healthier.
Finally, some love diving in Hawaii with frequent sightings of larger marine animals and numerous accessible beach dives that rival boat dives. Some divers take the time to discover the incredible diversity of marine life canouflaged in and around the coral and lava. Some hate it because almost all the coral is hard coral, no flowing gorgonia or sea fans, and duller color than the Caribbean, South Pacific, and Red Sea and with temperate waters generally between 72 and 80 degrees.
Come with an open mind and go with a guide, even when going on shore dives. You will see more than twice what you would see on your own (not selling, just telling you what I have learned over 20 yrs). It takes years to develop your mind and eye to spot many of our most unique critters. Don't worry if the viz is 30 feet or 100 feet. most times you will see things within inches or 15 feet of you. Some of our highlights: Turtles, dolphins, whales (Jan-Mar), mantas, eagle rays, lionfish of two varieties (they are native here-please do not remove them), frogfish, about 30 different species of eels-usually see 3 to 6 on any given dive, Triton's trumpet snail, Helmet conch, day and night octopus, rarely seahorses, nudibranchs of all kinds and sizes, 100lb + jacks, reef sharks, Galapagos sharks, hammerhead sharks, plate, pilar, rice, lobe, encrusting, razor, and other corals, 5 species of lobster, hundreds of species of crabs and shrimp, planktonic creatures of all kinds.
Winter temps average 70 to 75 degrees and most folks are more confortable in a 3 or 5 mm full suit. Keep in mind a shore dive may last more than an hour in 40' or less. Summer temps average 78 to 80 degrees. Some dive in shorties but most still prefer a full polar fleece or 2 to 3 mm suit.
Pick your preference and have fun!