Sandbar/ˈsændbɑːr/ Definition 1 of 1Pro Tip 1/3Natural Formation Sandbars are natural and form over time, sometimes visible above water. Birds often rest on the sandbar at low tide. Pro Tip 2/3Navigational Hazard Sandbars can be dangerous for boats as they're shallow and can cause grounding. The captain avoided the sandbar to prevent ship damage. Pro Tip 3/3Temporary Landscape Sandbars can change shape or disappear with strong currents and tides. The sandbar wasn't there last summer.