A swim platform makes an excellent addition to any pond or swimming hole. Using materials that have been treated against water will ensure a long-lasting platform. The size of the platform will depend on several factors like your budget. Float barrels can be found at most hardware stores or pool supply stores. The heavier the platform, the bigger the barrels you will need to use. Putting a cover like AstroTurf will soften the sitting surface and help protect the wood.
Determine how big of a platform you would like to build. A good standard size is 6 feet by 6 feet. This will allow several people to sit on it at the same time and when one person climbs onto it the opposite edge will not pull too far out of the water. Larger platforms can also be made.
Cut the wood into the appropriate lengths. For a 6-foot platform you will need 25 6-foot lengths of 2x4. You will also need four 6.5-foot lengths of the 2x6 wood. Treated wood is preferred as it will be sitting in water constantly. For larger platforms you will need different amounts and sizes of wood to fit the intended size.
Screw together the 2x6s to form a square. This square should rest with the 2-inch portion of the wood on the ground. Use two cut lengths of 2x4 to act as supports by screwing them in position across the center.
Attach the 2x4 lengths to the square frame side by side with the widest face pointing up. Screw them to both the frame and the midsection support. Attach the AstroTurf to the top of the 2x4s. Use screws that are weather-treated as they will be constantly in the water. The size and number of screws will depend on the size of the platform.
Sit the platform on the barrels that are in the water. The weight of the wood will prevent the barrels from floating away. The barrels will keep the wood from sinking.