This map was created by me, Aimbrot and R!dd!ck, it is the first map I ever released, and I'm a bit proud of it.
Just put the mg_boatrace_scramble.bsp into your CS:S map folder, which is located at: ?:\Program Files\Valve\Steam\SteamApps\*STEAM NAME*\counter-strike source\cstrike\maps\ or similar folder structures.
The goal of the map is to win the boatrace. Since there are only 6 boats to drive with, we built a bar and a bowling lane for you. But if you don't watch out, you will wake up in hospital.
W,A,S,D - Steering
MOUSE2 - Motor shutdown