A challenge build map where you try to build a boat that will survive a tsunami.

This download looks like an addon. You need to extract the downloaded zip and put the addon folder in your Garry's Mod addons folder. You should end up with a directory structure similar to below:

  • steamapps
    • common
      • garrysmod
        • garrysmod
          • addons
            • <-- Addon folder!
              • e.g.
              • lua
              • maps
              • materials
              • models
              • etc

Don't know where the Garry's Mod folder is or how to extract zip files? See more useful installation tips.