Yeah, it pretty much travels in a straight line, unless you turn the rudder to make it go in circles. As i recall, the diving fins are weighted, which drives the boat under the water, at which point a 'periscope' with a vane on it acts as a lever to bring the dive fins up again, thus resurfacing the boat, and this 'dive and surface' action continues until the battery runs out, or you get bored.......