What Sea Is Around Phuket?

Phuket is a top destination for beach holidays in Thailand. The island is blessed with natural beauty that’s definitely worth seeing — national parks, nature reserves, scenic viewpoints, and, of course, beaches for every taste. Thailand’s surrounding waters are quite diverse, so before your visit, it’s helpful to understand what sea surrounds Phuket and what you should know to ensure a safe and enjoyable trip.

What Bodies of Water Surround Thailand?

Let’s start with Thailand’s maritime geography and how it relates to Phuket. Thailand is located on two peninsulas — Indochina and the Malay Peninsula. The shores of Indochina are washed by the Gulf of Thailand, which is part of the South China Sea and belongs to the Pacific Ocean basin. The eastern part of the Malay Peninsula is also washed by the Gulf of Thailand.

The western coast of the Malay Peninsula, however, is washed by the Andaman Sea, which is part of the Indian Ocean basin. It connects to the South China Sea via the Strait of Malacca. The Andaman Sea is what surrounds Phuket. This sea is considered semi-enclosed, with its shores partially surrounded by land.

The calm waters of the Gulf of Thailand are ideal for families with children. However, the eastern coast lacks the refreshing sea breeze that comes from the Andaman Sea.

The Andaman Sea covers an impressive area of over 600,000 square kilometers. Its average depth is 1,043 meters, and the maximum depth is around 4,500 meters.

Off the coast of Phuket, the water temperature ranges from +26°C to +29°C (79–84°F), making it possible to swim year-round. For more details, check out our article on Monthly Weather in Phuket to choose the most comfortable time to travel.

So, if you’re wondering what sea or ocean surrounds Phuket — it’s the Andaman Sea, part of the Indian Ocean.

Sea Conditions by Season

Phuket’s tropical climate divides the year into two main seasons — dry and wet.

During the high (dry) season from November to May, conditions for swimming are ideal. Most beaches in Phuket have calm seas without strong waves. This is the safest and most comfortable time, especially for families with children. If you dislike waves and prefer a relaxing beach chill, this is your season. Choose beaches from our guide, and you won’t be disappointed.

In the low (wet) season from May to October, the southwest monsoon takes over the island. It brings rain and, due to strong winds, waves can reach up to 3 meters (10 feet) high. This is when knowing what sea surrounds Phuket becomes especially relevant. Our selection of wave-free beaches will come in handy. These beaches are located in small coves protected by rocks, so waves don’t form, and the water stays calm year-round.

What Lies Beneath the Andaman Sea?

The Andaman Sea is usually calm and warm, except during parts of the low season. But it holds some secrets. Did you know there’s a dormant volcano on its seabed? Its activity in 2004 triggered one of the most devastating tsunamis in history.

Geologists believe that Phuket’s unusual islands and bizarre rock formations are the result of ancient volcanic activity. After the 2004 tsunami, special buoys were installed around 1,000 kilometers offshore. These devices transmit satellite data and help detect underwater tremors and the formation of large waves — just in case nature stirs again.

There’s another hidden danger to be aware of — rip currents. These are fast-moving channels of water that pull away from the shore and can sweep swimmers out to sea. The key is not to panic and to know how to act — but it’s best to avoid them altogether. Read our article Rip Currents: How to Stay Safe for more information.

Things to Do in the Andaman Sea

The crystal-clear waters of the Andaman Sea are perfect for exploring marine life. Snorkeling — swimming with a mask and snorkel near the surface — is accessible to everyone and offers a glimpse into the vibrant underwater world. No special training is required, and the experience is full of color and excitement. Find the best snorkeling spots in our article Where to Snorkel in Phuket.

Diving is a more serious adventure, allowing you to explore deeper into the sea. Phuket and the nearby islands offer excellent dive spots. Check out the best diving spots or book a guided excursion below.

The low season, from June to September, is surf season. For wave seekers, it’s especially important to know what kind of sea surrounds Phuket. Find out where to surf on the island in our surfing guide.

In short, the beautiful Andaman Sea welcomes you year-round — just remember to stay cautious and prioritize safety when enjoying the open water.