SINGAPORE - What was meant to be a regular excursion for Mr Isaac Leong and his family turned into an extra special one when the estate planner found out that he was the 20 millionth visitor to Resorts World Sentosa's gated attractions on Thursday.

Mr Leong, his wife, mother-in-law, sister-in-law and two children were greeted with applause and a gift hamper worth more than $1,500 when they entered the resort's S.E.A. Aquarium for their first time. The aquarium is one of RWS's three gated attractions, alongside Universal Studios Singapore and the Adventure Cove Waterpark.

"It's a pretty pleasant shock," said Mr Leong, 38, whose family was there partly to celebrate the birthday of his mother-in-law, Madam Colleen Soh, who turns 64 on Friday. "We're very touched and thankful."

His wife Madam Geraldine Heng, a 36-year-old housewife who home schools their nine-year-old son and seven-year-old daughter, added: "My son has been pestering us to come ever since my mother showed him photos of sharks she took in Sydney."

Staring at the scalloped hammerhead and grey reef sharks swimming around him, the couple's son Josiah said: "It's cooler in real life."

The family also received annual passes to the attraction and a VIP tour, which included a visit to the aquarium's jellyfish breeding lab.

The S.E.A. Aquarium, which opened in November 2012, will launch themed conservation months, starting with a shark-themed one in August. Activities will include performances by Ms Cristina Zenato, a "shark whisperer" from the Bahamas, and the introduction of a new programme that will allow visitors to swim alongside sharks.

Vice-president of Attractions at RWS Mr Jason Horkin said: "It's not dangerous. Sharks typically don't attack people. Visitors will also have multiple safety divers with them."