As someone who’s into calisthenics only, the park is my default training ground all year round. There’s always enough apparatus for training a wide variety of fundamental bodyweight exercises which you simply cannot get anywhere else. You can even carry gymnastics rings along and hang them on one of the swings or pull-up bars to complete the experience.
But there’s this guy who owns a bar on a beach I usually go to. He recently set up an outdoor gym complete with a bench press, a pull-up bar, and a rack with barbells and dumbbells of various weights. Anyone is welcome to use them for free. He actually made the weights himself using concrete, and solid pieces of wood for the bars. It’s quite impressive.
Anytime I’m there I just set up two barbells parallel to each other in the sand to create a pair of parallets, which I can then use for L-sits, straddle Ls, tuck planches, and push-up variations. I then proceed with my upper body pulling exercises, front lever and back lever training with the pull-up bar. I also realised training pistol squats in the sand is slightly more difficult since it doesn’t provide a level surface to plant your feet. But since your core is tasked with more work to keep your centre of gravity stable throughout the movement, I gladly accept the challenge.
You also do have your fair share of long stares from hotties on the beach. You only have to make sure it doesn’t get to your head and try to pull off movements you’re not strong enough for. You’re only going to feel stupid for hurting your wrist or shoulder girdle just because you were trying to impress some girls.