Did you build one? Linked in the next line is how I attached it to land so you don't have to swim out!
   • How to Build and Attach a Dock to Lan...  

What you will need
11 pieces of 2x8 at 10 feet long
22 pieces of 1x6 decking at 10 feet long
2 1/2 inch decking screws
4 Barrels (45-55 gallons) i found mine on KIJIJI for 24$ each
Measuring tape
Mitre or Circular Saw
Drill
100 Feet of Dock Rope.