Snorkelling can be enjoyed in sheltered bays all around Phuket. It is particularly enjoyable at easily accessible reefs at Patong, Karon and Kata Beaches. Fins, mask, and snorkel can be rented on a daily basis from shops all over the island. Full and half day trips are available to the islands surrounding Phuket. Most popular are Ko Hae, Ko Racha Yai, Ko Khai (a hidden gem in Phang Nga Bay), and Ko Phi Phi. There are many tours available at very cheap rates and speedboats will be filled with up to 65 people. Research your options before signing up for any tour.
Agencies sell all-inclusive day trips from all over Phuket. Prices for group tours range from 1,400-3,900 baht. Quality and safety seem to correlate with prices paid. The lower-end speedboat tours take approximately 30-35 passengers per 2-engine speedboat and 50-60 passengers on 3-engine speedboats. Very cheap tours take over 100 people in a speedboat. The higher-end tours take approx 15 to 18 passengers on 2-engine speedboats. Insist on knowing the exact number of guests that will be on the boat. Keep in mind that tour desks will tell you anything to get your money, as they receive up to 65% commissions from the lower-end tours. It is always best to contact the dive company directly to ensure that you are getting what you pay for.
The more people on the boat, the longer it takes to get on and off at each stop, thus lowering the amount of time you get to spend off the boat. A packed boat is not very fun or safe when there are large waves.
Private companies providing small group tours are few. Full day tour prices range from 3,200-3,900 baht (no discounts are offered. Can only be booked direct). The tours include stops at all the major sights, higher quality lunches (from picnic to seaside sit-down restaurant meals), full sets of snorkelling gear, minibus transport, fresh tropical fruits, snacks & drinks on board, foreign owner/guide, small groups, attention to safety, and national park fee. Prices vary based on services, amenities and extras are provided.