I believe the Aquaventure expansion (Trident Tower) will be located between Dolphin Bay and the The Royal Atlantis Towers. You can see the available space in this layout:
The land clearing in the satellite imagery will probably be the gateway that leads to Trident Tower. There's still potential for the dolphin show (https://www.inmotionent.com/project/atlantis/) to be built in that area as well because the Trident Tower seems narrow and close to the beach.
Source: https://eliegamburg.com/the-royal-atlantis