In the cold, choppy waters of Alaska’s Resurrection Bay, all eyes were on the gray water. A team of researchers watched for one thing only. It wasn’t a spout from humpback whales that power through this scenic fjord, or a sea otter lazing on its back, munching a king crab.

Is that a narwhal tusk? No. The spear-like projection emerging from the water is part of a five-foot-long, bright pink underwater sea glider. The glider carries a large sensor that measures carbon dioxide levels in the ocean. And this one just completed its first overnight mission.

Team members aboard Nanuq, a University of Alaska Fairbanks research vessel, haul the glider onto the ship. They open the 130-pound shell and remove a white cylinder. This cylinder is like a miniature ocean laboratory. Seawater flows through it. Membranes separate water from gases. Tiny devices collect data. Someone rushes the cylinder inside Nanuq’s cabin to download the new information it contains.

The glider works in the water the way a drone does in the air. It is an autonomous vehicle that can dive to 3,281 feet and roam remote parts of the ocean. It collects information about ocean chemistry. Scientists are keen on monitoring acidity levels in the world’s oceans. As concentrations of carbon dioxide rise in some areas, acidity increases. That can damage sea life, especially hard-shelled creatures like crustaceans.

The glider represents a major step forward in ocean monitoring because of the depths it can reach. In the past, these measures were taken mostly from ships, buoys, and moorings tethered to the ocean floor.

God designed the seas to help keep Earth’s climate in balance. When carbon dioxide (C02) rises in the atmosphere, the ocean absorbs some of it. That helps lower temperatures on land. But if some ocean areas trap too much C02, they can get out of balance. People study the chemistry of air, soil, and water. They try to determine whether imbalances are occurring—and which ones may need intervention to resolve.

The sensor used in the glider is the same as those found on any ship or lab working with CO2 measurements. The challenge for this project, says Richard Feely, is to record the measurements on a glider with the same degree of accuracy and precision as tests on board ships. Feely is the National Oceanic and Atmospheric Administration’s senior scientist at the agency’s Pacific Marine Environmental Laboratory in Seattle, Washington.

There is no GPS unit inside the underwater autonomous drone. Instead, after being programmed, it heads out on its own to cruise the ocean according to the navigation directions. It knows how far to go down in the water column, when to sample, and when to surface and send a locator signal so it can be retrieved.

As the drone tests were underway, the U.S. research vessel Sikuliaq, owned by the National Science Foundation and operated by the university, conducted its own two-week mission in the gulf. It takes carbon and pH samples as part of ongoing work each spring, summer, and fall.

Those methods are limited to collecting samples from a fixed point. The glider will be able to roam all over the ocean and provide researchers with a wealth of data on the ocean’s chemical makeup.

The vision is to one day have a fleet of robotic gliders operating in oceans across the globe, providing a real-time glimpse of current conditions and a way to better predict the future.

(Oceanographers Andrew McDonnell, left, and Claudine Hauri, middle, along with engineer Joran Kemme work with the underwater glider as it is pulled aboard the research vessel Nanuq from the Gulf of Alaska. AP/Mark Thiessen)