Tiger sharks can boldly go where no diver has gone before—or is likely to go anytime soon. That makes them great research assistants for marine scientists. In fact, they helped confirm the discovery of the largest known seagrass meadow in the world.

The seagrass is in the Bahamas. Scientists used satellite observations to get a rough estimate of the size of the beds. Divers took more than 2500 plunges into the clear, shallow Caribbean waters to confirm the satellite maps.

Even so, coverage was limited. It was too expensive or time consuming to go over the entire region. So the scientists got some extra help. They attached video cameras to seven tiger sharks—the largest sharks to routinely patrol the Bahamas Banks. Tiger sharks like to hang around seagrass beds, making them good tools for checking things out.

The combined observations suggested that a single seagrass meadow covers up to 35,000 square miles—an area the size of Indiana. That would make it by far the largest seagrass meadow yet found—accounting for 40 percent of all the world’s known seagrass beds.

That’s important because seagrass is far more efficient than tropical rainforests at storing carbon. That keeps the carbon out of the atmosphere, so it can’t contribute to our changing climate. The researchers estimate that the new meadows could be hoarding roughly 20 to 25 percent of all the carbon held in seagrass beds—beds mapped with the help of tiger sharks.