Merlin Entertainments Group
2019 - SeaLife Malaysia - (1/22/19) Merlin will open a new attraction at the Legoland Malaysia Resort in April 2019 with the introduction of SeaLife Malaysia. The new marine life attraction will take up a 2,123 square-meter two-story building features more than 25 different display tanks.
(5/15/17) According to the local news Legoland Malaysia will begin construction next week on a new marine life aquarium attraction to open in 2018, with the official announcement to come from Merlin sometime this fall. While at first this could be taken as the clear sign that they will be opening a new Merlin branded SeaLife Aquarium next to the park as a second gated attraction, some of the Legoland theme parks have instead opted to build unique attractions that take guests on a simulated submarine voyage through what is essentially a giant themed aquarium full of live fish species. One named Submarine Adventure just opened at the new Legoland Japan park last month (follow this link to see a video of that attraction) while the Windor park opened similar attractions in 2001 under the Atlantis Submarine Voyage name.
I guess we'll have to wait a bit longer to find out if this is a new ride at the existing park or an entirely new ticketed attraction.