Off the southwestern shore of Kauai, the restricted island of Niihau Island has excellent off-shore snorkeling with some of the clearest water in Hawaii. The waters are known for high visibility because of the low rain fall and limited farming runoff. But, since it is a protected privately-owned island, it is prohibited to land on any shores unless you have permission. Ni’ihau Island is located 17 miles off the southwest coast of Kauai across the usually rough, deep-water Kaulakahi Channel.
In addition to the main island of Ni’ihau, there is a small island of Lehua off the northern coast, an ancient sunken volcanic crater, that many of the dive boat charters frequent. The dive boats head to Lehua partly because its the main island blocks the southern swells from Lehua and partly out of respect for the native Hawaiians living on Ni’ihau The Island of Ni'ihau is maintained only for native Hawaiians, but snorkelers are permitted offshore. When snorkeling off Ni'ihau, you might encounter manta rays, monk seals, Galapagos sharks, dolphins, wrasses, parrotfish, butterflyfish, angelfish and tangs.
Off Lehua Island, there are three main snorkeling dive sites. First, off the northwestern point, there is the Key Hole snorkeling dive site in waters from shallows to 30 feet deep which has nice drift currents along with reef fish and sharks. Second, off the west coast, there is the Pyramid Point snorkeling dive site in waters from shallows down to 50 feet deep with a rocky bottom. Lastly, and most popular with dive boats, the Lehua Slope snorkeling dive site off the south shore starts in 10 foot deep waters and heads out to 55 feet deep. That dive site is known for reef sharks, eagle rays and occasionally whale sharks. Just watch out for its strong currents.
To reach the snorkeling off Ni'ihau Island from Kauai, start by flying into Lihue airport (LIH). There are direct flights from Los Angeles, San Francisco, Denver, Seattle and Honolulu. While most visitors to the island rent a car, it is possible to use the public bus but keep in mind that its small and slow. Then, you will need to use one of the charter boat tours out of Port Allen near Poipu, Kauai. There are three options for getting to the waters offshore of Niihau. There are two full-day charter boat tours that include a cruise of the Napali coast, which means the actual onsite snorkeling time is less than an hour at Lehua Island. Also, watch out when booking these charters since some booking agencies are offering steep discounts, but these are really combined with timeshare tours. There is also Seasport Divers which heads straight to the offshore waters. This charter is aimed at scuba divers, but snorkelers are also welcome. The time spent onsite is several hours. It typically takes about 2 hours each way by boat across Kaulakahi Channel to reach Ni’ihau.
There is another option for actually snorkeling on Ni'ihau. The Robertson family, which manages the Island of Ni'ihau, operates Niihau Helicopters Inc. This helicopter charter service provides a quick tour of the island and lands on a secluded beach where you can land and snorkeling on the reef.
Before snorkeling at Ni'ihau Island, make sure to check the current surf report. The waters off Kauai are known for potentially strong currents, high surf and rogue waves. Luckily, there are excellent up-to-date surf reports that can provide guidance on these adverse conditions. WIth the usually rolling surf, it is strongly discouraged to use open-tube snorkels which are common at snorkel rental locations -- only use snorkels with a dry-top splash-guard and a sump purge-valve in the mouth piece. In addition to changing surf conditions, a Ni'ihau Island snorkeling dive may expose you to sharp coral reefs and you may encounter sharks, such as whitetip reef sharks, galapagos sharks and tiger sharks. Most snorkeling shark attacks in Hawaiian waters tend to occur near spear-fishing snorkelers, so be aware of the activities of others in the water.
Overall, Niihau Island is the 12th most popular snorkel dive spot of all 23 snorkeling dives in Kauai.