Are these the only options? Strange...
Horse riding! is rare for most. From my own 3 months experience, the horse to human interaction is nice. One might never get to ride horse again, since they are no longer means of transport. Risk of falling down from horse exists. would the horse riding happen within college campus?
There is one more subtle point: hymen,(though its really moot and silly) is your local culture obsessed about it? Some cultures are...
Swimming also has same problem, its not a necessity, in many regions of world. But a better option. Unless you are in a country where they have separate pool/ separate timing for women, it might not be of much use in future. Swimming, the same rule applies for men (no free mixing and seeing). Make sure, the college maintains the pool often and water is cleaner. Avoid in summers(water scarcity) to avoid water borne diseases...
Just some points, that comes to my mind...
