I would like to visit the papal (I think?) gardens/villas but I’m really confused about what is what. I don’t really care about going to the actual papal residence. We are just looking for a day or half-day trip (not overnight) that involves those pretty gardens and then maybe some paddle boating on the lake. Any help on what and how to see/do this?
The Vatican by Train tour is your best bet for seeing the Barberini Garden of Castel Gandolfo. In fact, I don't think you can have access without the tour. I do not know about paddling on the lake.
As best I can tell, the official Vatican by Train thing is sold out for the 5 days we are there in mid-June.
Perhaps the Villa d'Este in Tivoli would suit?
When we are in the Roma area we always stay at a b&b in the Castelli Romani in Ariccia. We have been to Castel Gandolfo many times. It is a nice place to visit and we like one of its restaurants.
The poster who suggested Tivoli has made a great suggest. It's easy to spend an afternoon there just browsing the gardens. Nearby is Hadrian's Villa, which is an emperor's hangout.
Another suggestion would be Ostia Antica, which is reachable by train or subway, just outside of Roma. It offers everything Pompeii offers minus the notoriety. However, it offers two amenities noticeably missing from Pompeii; 1. a sea breeze, and 2. shade.
Another suggestion would be a 75 minute train ride to Orvieto, which is located on a mountain top. You take the funicular located across the piazza from the train station to go up to the town. Very nice.
Go and have fun.
Buon viaggio,
aipease1, I haven't done this one yet but it does look like you can rent paddle boats on Lago Albano. These two blog pieces are from a year or two ago, respectively, but may be helpful? You don't need a Vatican tour to get there/enjoy the lake but I would purchase round-trip train tickets (Trenitalia trains) in Rome; I'm unsure that the Castel Gandolfo stop has ticketing services (maybe someone else knows?)
https://theculturetrip.com/europe/italy/articles/how-to-spend-a-day-in-castel-gandolfo/
https://anamericaninrome.com/wp/2016/04/day-trip-from-rome-castel-gandolfo/