I said it before and I'll say it again, they should just figure out a way to get an "underwater viewing" area next to the lagoon like they have at SeaWorld. Use the same Parralax Tech/screens that the ride in Hollywood has, have the mosasaur peacefully swim by most of the time and then occasionally ram the screen with a water burst effect. This way you dont ruin the "Map of the park by having the mosasaur lagoon as the main lagoon and it somehow connect to the River adventure. Also gives a cool down station to the area. You are welcome Universal Creative....
View attachment 17880
Edited the original image with a quick Photoshop Mosasaurus