Strange lag spikes when underwater in underwater condo?

I get horrific lag spikes when i’m underwater in the new condo. On the surface and INSIDE the condo i get a good 85 fps then when i go into the ocean i drop down to a horrifying 25.
Is this normal? Suggestions to fix could be to lower the quality of other condo’s that you are not in, lower quality of texture/models of stuff when you’re far off it and stuff. Maybe that’d help.