The Sims 3 Permanent Mermaid Lifetime Reward
Lifetime Happiness Points: 5,000
This LTR can only be purchased by Sims that are already Mermaids. It will remove the requirement that your Sim enter the water in order to avoid transforming back into a regular Sim. At such a low cost, it's a no-brainer buy for any Sim that you want to stay a Mermaid to avoid having to get another piece of Kelp.
Share your tips about this Reward to aid your fellow Sims players: