Archaeology, culture, having a different vacation world. I've sent quite a few households there and they do different things. Most often, I send honeymooners there to the romantic villa with a pool and they come back with kids.
I usually send typical vacationers to the market/bar and to the museum. They spend a lot of time relaxing. Maybe they go a little bit into the jungle. Most adventurous sims go farther in. I actually haven't played with the temple. They usually go swimming at the Omniscan pools. Sometimes they go into the other paths. They often camp over night.
I have sent groups exploring the jungle a few times. Two have died. A lot of families go there and just find ways to relax and spend time together since they are on vacation. Maybe they get a little familiar with the locals.
One sim married a local and brought him back. I completely disliked the specific sim that she married. It's hard to explain, he just was not nice at all. They had a baby who is named after him, but I disliked that sim enough that when he caught on fire doing laundry, I just said, "Ok, good riddance." That's not a reflection on Selvadoradians though, just that specific character. The kid is great though and is half-Selvadoradian.
It all varies but my vacations with the sims are typically more chill. I definitely spend a lot of time with the culture. It's nice to have the option to be more adventurous and some are but typically they bring tents, get supplies and go camping. They try to see how long they can stay in the jungle. Those are only sims who are more prepared and intrepid or more expendable.
