How do I find kelp on The Sims 3 Island Paradise?

 kelp can be found underwater so your sim might find it while scuba diveing

You can buy kelp at the grocery store.  Mermaid kelp can only be received by BFF a mermaid/man and asking them about their body parts (not exactly sure about the exact phrase cause my game is closed at this moment.

Thanks so much! Appreciate it