Here is a portable fitness tool that you can use indoors and outside for bodyweight training. The Tunturi Pro Suspension Trainer can be attached to a door, tree, or bar. You can use it to train on the beach, in the woods, and anywhere else. You get handles, foot loops, anchor cords, strings and a pulley.
The Tunturi Pro Suspension Trainer is adjustable to fit your needs. It weighs only 4.5kg. You can find out more about it here.