Northeast of Hanalei on Kauai, the snorkeling at Princeville Hotel Beach (Puu Poa Beach) is known for its good reefs and average snorkel experience. If you're lucky, when snorkeling off Puu Poa Beach, you may encounter goatfish, barracuda, parrotfish, white tipped reef sharks and, the much less frequent green sea turtles.
The best snorkeling off Princeville Beach is heading out one of the channels, such as on the south end of the beach. At low tide, the reefs are pretty shallow, so finding channels is important. For the most part, the visibility of the water close to shore is pretty poor. The visibility get better the further out you head. Also, from September through May, the surf off Ke'e Beach is affected by seasonal northwest swells that kickup the large waves and generate strong currents so make sure to exercise caution.
To reach the snorkeling in Kauai by air, fly into the Lihue airport (LIH). There are direct flights from Los Angeles, Denver, San Francisco, 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. Plus, most of the main snorkeling beaches are well off the bus route requiring some hiking. If you do rent a car, make sure to leave the inside empty when at the beach to avoid attracting break-ins.
To reach the snorkeling at Princeville Hotel Beach, head west on Kuhio Highway (SR56) through Kapa'a towards Hanalei. At Princeville, turn right heading north on Ka Haku Road into Princeville Resort for 2 miles to the end of the road. The public parking is just prior to the main Princeville Hotel parking lot. There is room for only 8 or so cars, so make sure to arrive very early. Alternately, if you're willing to buy a lunch, you can use the Princeville Resort Hotel valet parking which is complementary with beach bar lunch purchase. By the way, there are two other dive sites nearby including Hideaways Beach and Queen Emmas Bath.
From the parking area, cross the main road and look for the public trail before the guard shack leading southwest towards the golf course and eventually down 150+ stairs to the beach.
Before snorkeling at Princeville Hotel Beach, 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 Princeville Hotel Beach 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, Princeville Hotel Beach is the 12th most popular snorkel dive spot of all 23 snorkeling dives in Kauai.