BIG SEA 5

Best months: Oct–Feb

Protected Area

Khao Sam Roi Yot Wetland

Why dive here

With 54+ marine species recorded in the area - including sea turtles, tiger sharks and pufferfish - BIG SEA 5 offers some of Koh Tao's richest wreck diving. Water ranges 29-31°C, warmest April, May, June.

Best timeOct–Feb

WetsuitA 3mm shorty or thin full wetsuit

Marine lifeSea Turtles, Tiger Sharks and Pufferfish · 54+ species recorded

Water29-31°C · warmest April, May, June

CharacterWreck dive · max 30m

Big Sea 5. We love a good wreck, especially one with a story, and this tanker delivers. She’s the old Masayoshi Maru No 2, a good-sized vessel at nearly 70 metres, now resting upright at 30m. Dropping down, you’ll first see the superstructure, a dark silhouette against the blue, before the details emerge. We always head for the bridge first, imagining the helmsman’s last view. Her holds are open, inviting you inside. It's dark in there, so good lights are essential, and a reel is smart if you’re venturing deep. You’ll feel the subtle shift in temperature as you penetrate, and the sound of your own bubbles echoes around you. Schools of fusiliers often swirl just outside the openings, flashing silver as they catch the light. Look for barracuda patrolling the deck, their eyes following your every move. We’ve spotted large groupers lurking in the shadows of the engine room. It’s a proper wreck dive, perfect for those comfortable with deeper profiles and a bit of overhead environment exploration.

Typical BIG SEA 5 Dive Profile

Illustrative profile based on site depth and type. Actual dive profiles vary - always follow your dive computer and training.

Safety Notes

Depth of 30m - Advanced Open Water certification recommended.

Wreck site - avoid penetration without wreck diving certification. Watch for sharp metal and entanglement hazards.

Always perform a 3-minute safety stop at 5m before surfacing.

Today06:0918:0411h 55m daylightGolden hour 17:36

BIG SEA 5 Wreck History

Year Sunk

2003

Vessel Type

tanker

Cause

scuttled

Tonnage

730 GRT

The vessel now known as the Big Sea 5 began its life in Japan in 1982, christened the Masayoshi Maru No. 2. This 70-meter coastal tanker spent years transporting fuels and other liquids before being sold to the Big Sea Co Ltd in Bangkok, Thailand, and renamed. As the Big Sea 5, it continued its service in the bustling shipping lanes of Southeast Asia, a reliable workhorse of maritime industry.

After a long and productive career, the tanker was retired. Rather than being sent to the scrapyard, it was given a new purpose. In 2003, the Big Sea 5 was thoroughly cleaned and prepared before being intentionally scuttled off the coast of Koh Tao. This sinking was part of a project to create a new artificial reef, aimed at relieving pressure on natural dive sites and providing an exciting new underwater attraction for the island's thriving dive community.

Resting upright on the seabed at a maximum depth of 30 meters, the Big Sea 5 is a fantastic wreck dive for advanced divers. The ship is largely intact, allowing for exploration of its deck, superstructure, and bridge. Over the years, it has been beautifully colonized by marine life. Large groupers and barracuda are often seen patrolling the wreck, while dense schools of fusiliers and snappers swarm around its highest points. The wreck's size and depth make it a rewarding and atmospheric dive, a perfect example of a vessel's successful transformation from industrial workhorse to vibrant marine habitat.

Reviews for BIG SEA 5

Conditions

Ocean conditions, forecast and tides for BIG SEA 5

BIG SEA 5 Ocean Conditions

Monthly averages for BIG SEA 5, sourced from Open-Meteo marine data + Copernicus Marine (EU) - nearest station: Open-Meteo marine grid (11.17, 101.33) (40km away)