A mudflat is a stretch of muddy or sandy ground along a coast that gets covered by water at high tide and exposed at low tide. When the ocean pulls back twice a day, it leaves behind these flat, glistening expanses of wet mud or sand that can stretch for hundreds of yards.

Mudflats might look empty and boring at first glance, but they're actually teeming with life. Clams, worms, crabs, and tiny creatures burrow into the mud, which is why you'll often see shorebirds like sandpipers and plovers racing across mudflats at low tide, poking their beaks into the mud to catch a meal. The mud itself is usually soft and sticky, making mudflats tricky to walk across without sinking in or losing your boots.

Many coastal cities were built near mudflats because they provided calm harbors for ships. People have also harvested clams and oysters from mudflats for thousands of years. While mudflats can smell a bit like rotting seaweed (that's bacteria breaking down organic matter), they play an important role in coastal ecosystems, filtering water and providing habitat for countless species. If you visit a beach with mudflats, check the tide schedule: you'll see a completely different landscape depending on whether you arrive at high tide or low tide.