The shortcut in this track is easy to spot, because of the ramp leading to it. Take the last ramp toward the tunnel in the wall, and right when you reach the end of the ramp, jump to make it into the tunnel. If you're racing against others, this ramp would be an excellent place to leave traps, just don't fall into them yourself!
Mario Kart 64 Shortcut Video Walkthrough Series for Nintendo 64
Mario Kart 64 - Koopa Troopa Beach Shortcut Video
