Per Safety Wise, the GSUSA rule book, scouts must be 14 years old to travel internationally. A 13-year old can plan for a trip, fundraise for a trip, but she must be 14 years old by the time the trip leaves. Safety Wise also emphasizes the importance of "progression" with scout troops -- that younger girls plan day trips, older girls plan trips within state, and only the high school-aged scouts are allowed to consider out-of-the-country trips. With 12 year olds included, this trip will not be approved by council. Some troops get around this by saying that it's just a "friends trip", but that is skirting the rules and could get them into trouble -- and they won't be covered by their scout insurance. Last thought on that subject: If your leader is breaking this rule, I'd want to know if she has all her scout leader training completed.
Safety Wise does not address the issue of girls and leader sharing rooms/tents, though some individual councils have added such rules. Personally, I think that's rather foolish because sharing a room is a good idea when kids are Brownies, and a "sometimes" thing for older scouts. Last night I supervised a scout overnight. We had one huge room (a scout hut) for everyone; if scouts and leaders couldn't sleep in the same room, then the overnight couldn't have happened. Furthermore, some kids are comfortable sleeping with friends, others are more nervous away from home -- my oldest wouldn't care a bit, my youngest likes to know that an adult is nearby.
Scout trips are not required to be educational. Troops take trips for all sorts of reasons: Sometimes they're about community service, sometimes they're educational, sometimes they're just for fun. What scouting emphasizes more than the educational component is the idea that the girls plan the trip themselves; that is, that they set the goal, raise the money, make the plans and see them through.
Would they be safe on Carnival? I've not sailed Carnival myself, but I've sailed several other cruise lines. They are very safe for kids in pairs during the day -- provided they understand the iron-clad rule that they must never, ever enter another person's cabin. After dark, I would make stringent rules about the whole group staying together. It's after dark when trouble happens for kids on cruise ships -- that's when older teens will come up with ideas like taking walks into dark areas or perhaps coming up with alcohol. But during the day, I wouldn't be worried about them being on the ship in pairs.
Would they be safe in Mexico? You have to realize that cruises only stop in ports for 8 hours or so. Cruisers don't go into the heart of the country, they don't see the real 3-world countries or islands. If they stay by the port, they're going to see beaches and touristy shops that aren't all that different from Myrtle Beach. Could they find drugs? Probably, if they sought them out, which I'm sure their leaders wouldn't allow, but people aren't likely to press drugs on 12-year olds. And we don't know whether the group plans to get off the ship at ports or not. If they were going to get off the ship and take part in an excursion, I'd have no problem with that -- for a slightly older teen.
