@katelynk005 I've moved your post to the Sims 3 PC tech section.
The main problem with the Island Paradise pack is the world of Isla Paradiso, which is so broken that it's almsot unplayable even on the strongest computers. But all of the features work just fine in any world that has space for them and deep enough water. A lot of players use those features in Sunlit Tides, or they download a player-made world.
There's also a fixed version of IP offered by a player who edited out all the most problematic issues. It comes as a save—you drop it into your Saves folder, and it doesn't influence your other content. You can download it here, or read about her edits and copy them into your own game.
https://forums.thesims.com/en_US/discussion/811253/removing-ip-lag
The other potential issue is the strength of your computer. Island Paradise is the third or fourth most demanding pack (far behind Pets and Seasons), and even without not running the world itself, the other features are still taxing enough. If you'd like an opinion on how your computer might be able to handle the pack, you can list your specs and the other packs you already have. Or, if you want to be more thorough, run a dxdiag, which will cover other issues besides the hardware itself.
https://help.ea.com/en-us/help/pc/how-to-gather-dxdiag-information/
would it work for sunset valley with a lot of stuff added? to be honest i never remember having issues with isla paradiso, and i dont have the best computer. i just want the mermaids and the scuba diving and the boats, and was hoping i could use that, but i dont think scuba diving works in sunset valley, and i dont think you can add diving spots personally.
@katelynk005 You can definitely add dive lots yourself, or you can build them. The only requirement is that the water is deep enough—I do think Sunset Valley qualifies, although Riverview does not. This tutorial by karritz is quite popular:
https://www.youtube.com/watch?v=xQYREabahSE&list=PLFT4tKkKX8Wvc78leOoIOzOBOtemfqERG&index=3&t=0s
I can't tell you how your computer might run with Island Paradise installed unless I know its specs. Sims 3 doesn't require a beast of a computer, but the most demanding packs simply won't run very well on low-end systems. You could also experiment, and uninstall if necessary.
here are my specs:
