Ko Samui, Thailand Photo Gallery. Ko Samui, Thailand is a new photo lightbox by Greg C Grace.Located in the Gulf of Thailand, Ko Samui is Thailand's second largest island. It's tropical white beaches, aqua waters, coral reefs and coconut trees add to its exotic appeal, making it a must see tourist destination for Southern Thailand It is surrounded by some sixty other islands, which compose the Ang Thong Marine National Park, Ko Phangan, Ko Tao and Ko Nang. Samui is a mix of natural paradise, pulsating nightlife and layed back sandy beaches. Click here to see more images from Greg C Grace.