Booked the premium trip. It was well worth the extra cost. We had done the normal trip a couple of days previous and the boat was packed well over 50 people on it. The premium is max 25 and is on a nicer boat. There is plenty of room for all the passengers. The guide Man was knowledgable and was a great guide. Spent time talking to the guests. Food was different to what trip advisor say, you get a Thai buffet that consisted of rice, chicken curry, tofu stir fry and fried chicken and a vegetable dish. Fruit for afters. Tea, coffee and water and biscuits through out the day. Start with going in the premium lounge where you can have drinks and sweet/savoury buns. Transfer to the boat and set off going on 5 different snorkle stops, freedom beach first and saw 2 turtles, sharks bay saw a large shark, then to pinnacle others saw 2 turtles at that bay, then to the Japanese garden, this was the best for coral and clown fish (not the orange and white ones like memo) then went to the island where you pay an extra 250b , clear water but not the best spot for snorkelling. Very picturesque though. I would fully recommend the premium tour if you want a nicer experience.
Overall Oxygen have it well organised they have multiple trips every day and appeared well organised.