From Visitor Arrival Centre, take the Yellow Line bus to Dolphin Lagoon. Similarly, if you are from the cable car station, take either the Blue Line or the Green Line to Siloso Beach before changing to the Red Line bus. Since Dolphin Lagoon is located adjacent to Palawan Beach, you may also use the beach train if you are coming from Tanjong Beach.
Dolphin Lagoon admission is inclusive of the ticket price to Sentosa Underwater World (SGD19.50). As the name suggests, the lagoon displays a collection of Indo-Pacific hump-backed dolphins (sousa chinensis a.k.a pink dolphins for their subtle pinkish hue) which were acquired from a Thailand marine theme outfit called Oasis Seaworld.
There is almost no basis to visit Dolphin Lagoon except during the "Meet the Dolphin" sessions. The sessions are held daily at 1100 hrs, 1330 hrs, 1530 hrs and 1730 hrs. Please ensure that your timing is correct so that you do not miss the show where you catch these adorable sea mammals performing various tricks.
As the session started, loud music was played to introduce two pink dolphins that gracefully swam across the lagoon while gesturing toward the spectators. A narrator equipped with a microphone would describe some factual information regarding these endangered animals. The tricks performed include carrying balls, jumping across a hoop, dancing above water, etc. Two volunteers would then be called up to participate with an activity with the dolphins. As a reward, they will be allowed to take photographs with the pink dolphins for free (others would have to pay and get wet in the waist-deep lagoon).
There are plenty of covered shades along the lagoon for the spectators so that you don't have to worry about the scorching sun.
Educational and interesting but not too impressive in my opinion.