Jet Ski
There is nothing like the feel of riding a high speed water vehicle as you take a tour of the island. Renting a jet ski equipment on the island is never a problem. Lamai, Chaweng, and Hua Thanon are places where you can easily obtain a jet ski.  

Scuba Diving
If you want to see the amazing underwater creatures of the island, the best activity for you is SCUBA. Some of the best diving schools in Thailand are located in Samui.

Sailing
Another hit among Koh Samui guests is sailing. Because one can be able to see a huge portion of the island while on a sail, this is a great option for those who will be on the island for only a limited time. Being out on the sea in a cruise ship or a luxury yacht never really goes out of style. If you prefer something low key, then opt for a catamaran instead.

Kite Boarding/Kite Surfing
The waters of Samui and its strong winds make riding a giant kite a phenomenal water activity. Samui has one of the best kite surfing schools in Asia, which is Kite Boarding Asia or KBA. The months of February to November are considered the best time to visit the island if you want to try this sport.

Paddle Boarding /SUP
If you want a workout that you can do outdoors while having fun at the beach, you can try standing paddle boarding.

Kayaking
Kayak tours are a fun way to get to know Koh Samui even better. There are plenty of kayak daytrip packages to choose from. One of the popular ones is the Angthong Marine Park tour.

Wakeboarding
A young but challenging sport, wakeboarding is a sure hit among sports fans as well. It’s difficult at first and can be frustrating if you can’t get up easily, but it’ll get better with practice. Koh Samui’s neighbor island, Koh Phangan, is a great venue for this sport. 

Flyboarding
Adrenaline rush lovers will surely go gaga over the different stunts they can perform while on the water.

Big Game Fishing
Many travelers come to Samui to catch big fish. The waters of the island are very rich and it is a joy to be able to have the chance to catch the biggest varieties of fish you will ever see.