Meet the Trideck: a 3-wheel skateboard that you can ride on grass, gravel, and at the beach. It has air-filled tires and a brake pedal. It gives you the feel of a skateboard but offers a lot of roll and shock absorption for a stable ride. It uses the same wheels as small bicycles, so you can replace them easily.
The Trideck has a rugged steel tube frame, detachable joystick handle, aluminum wheels, a steering tension turn-knob, and an aluminum brake pedal. The above video shows how it performs. You can find out more about it here.