Southwest of Lihue and southeast of Koloa on Kauai, the snorkeling at Poi'pu Beach County Park is very popular with tourists. Although the most popular snorkeling dive site in Poipu, it is probably the worst. It is known for its poor water clarity, limited marine life and almost no coral growth. The Poipu Beach snorkeling can also be a very crowded affair, especially at high tide as the beach space shrinks. At the very family-friendly Poipu Beach Park, there are two twin coves ranging from 3 to 10 feet deep. The best Poipu snorkeling it in the righthand, western cove. While snorkeling off Poipu Beach, you may encounter ornate butterflyfish, humuhumunukunukuapua’a (Hawaiian state fish aka rectangular triggerfish), moorish idols, wrasse, zebra moray eels and occasionally green sea turtles and monk seals. Since some of the sand is trucked in, water clarity can be a continual issue here.
There are several large public parking areas, but they do fill up quickly in the morning. Also, from May through September, the surf off Poipu Beach is affected by seasonal southerly 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, San Francisco, Seattle, Denver 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 Poipu Beach snorkeling from Koloa, head south on Poipu Road. Turn right on Ho'owili Road to the end where there are two parking lots for Poi'pu Beach County Park.
Before snorkeling at Poipu 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 Poipu 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, Poipu Beach is the 4th most popular snorkel dive spot of all 23 snorkeling dives in Kauai.