Koh Racha Noi Marina Bay and Maritas Rock are 2 dive sites in 1

Marina Bay and Maritas Rock are one of the most popular dive sites on Koh Racha Noi and are always ranked for best scuba diving in Phuket. The two spots are really two dive sites in one.

Marina Bay is sheltered by the island, while Maritas Rock is in the open.

The depth at Maritas Rock goes all the way down to over 130 feet (40 meters) and into the open sea. Due to its depth and strong currents, this dive site is recommended for advanced divers only.

maritas rock manta ray

About Marina Bay and Maritas Rock at Koh Racha Noi

Composed of granite rock, the bay situated in the northwest region of Racha Noi is home to a variety of coral species such as leather and fire corals, sea fans, pore corals, and sea whips. While water currents inside Marina Bay are usually mild, outside at Marita’s Rock they can be quite powerful. This is a good thing for this dive site: The current attracts manta rays and other bigger fish.

This gives this area the nickname “Manta Bay”.

Maritas Rock has many swim-throughs for divers and is home to a wide array of marine life. 

Marina Bay & Maritas Rock dive site brief

  • Access: From boat
  • Maximum depth: 130 feet/ 40 meters (60 ft/18 m in the bay)
  • Visibility: 49 – 98 feet / 15 – 30 meters
  • Dive time: 45 – 60 minutes 
  • Certification level: Advanced Open Water
  • Current: light in Marina Bay, strong outside the bay
  • Type: reef, pinnacle
marina bay leopard shark

The dive plan for Marina Bay and Maritas Rock in Phuket

On a typical dive, divers begin in the bay and descend on a mooring line. The bottom is usually sandy at around 33 and 39 feet (10 – 12 m) deep. Along the sand patches, you will find coral bommies and staghorn coral. After exploring the bay, towards the southern end of the bay, the scenery transforms into a rocky underwater landscape.

Located approximately 66 feet (20 m) south of the bay, Marita’s Rock begins at a depth of around 79 feet (24 meters) and goes all the way down to the recreational diving limits of 130 feet (40 meters).

Here, the drop-offs are much steeper, and you’ll notice a change in the currents. They become much stronger and divers aren’t sheltered anymore by the bay.

The Koh Racha Noi rays can typically be seen at the southern end of Marina Bay or Marita’s Rock, where depths are around 66 to 100 feet (20 – 30 m). These majestic creatures tend to feed on krill and jellyfish, which is why they are drawn toward dive sites that experience currents.

Marita’s Rock is adorned with a plethora of gorgeous swim-throughs wound between the granite boulders. And if you make your way to the end up north, another tunnel awaits.

At the end of the dive, during the safety stop it’s best to hover around the peak of Maritas Rock. You may see more rays gliding by.

What to see at Marina Bay and Maritas Rock in Koh Racha Noi?

If you’re lucky and keep an eye out, the sandy bottom of this bay may reveal bluespotted stingrays and scissortail gobies in a pair. Keep exploring further in-depth to discover pipefish, cuttlefish or even come across a majestic manta ray. Common reef inhabitants like parrot fish, snapper, angelfish, butterfly fish, and neon fusiliers can also be found in abundance.

Don’t forget about the small ones either – nudibranchs might be hiding among rocks as well.

maritas rock whale shark

However, most divers remember the big animals. Maritas Rock is the last dive site before the Similans and the open Andaman Sea. Therefore, bigger fish can be spotted at this dive site frequently. Leopard Sharks crave the comfort of sandy patches, and you can typically be seen on any given day. On occasion, you may see a whale shark swim by, or witness blacktip or whitetip reef sharks coming toward the reef.

When is the best time to dive at Marina Bay and Maritas Rock?

The best time to dive at Marina Bay and Maritas Rock is from November to April during the dry season. The rest of the year is filled with strong monsoon winds from various directions. Additionally, some of the bigger animals like whale sharks migrate during the winter months and therefore increase the likelihood to pass by Maritas Rock in Koh Racha Noi.

Related dive sites

If you are interested in seeing sharks or other bigger animals, Shark Point is great for sharks. Racha Noi South Tip is famous for manta rays. Advanced divers also need to check out the King Cruiser wreck.

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