Tethys floats at the surface in Monterey Bay.

A new breed of undersea robot promises to give oceanographers a deeper understanding of ocean life by going faster, farther, and longer than its predecessors--and by doing a little thinking all on its own.

Scientists at the Monterey Bay Aquarium Research Institute say their newest autonomous underwater vehicle, called Tethys, introduces a new class of AUV that will take their oceanic research to a whole new level.

The two types of AUVs that researchers have relied on in the past both had their drawbacks. Propeller-driven vehicles could travel at a relatively quick pace and carry big payloads but could only be out at sea for a few days. Another type, called gliders, could endure weeks-long expeditions but were seriously lacking in the speed category. Traditional gliders top out at about 0.5 mph, according to the team's statement.

MBARI&39's Jim Bellingham, Thomas Hoover, and Bret Hobson work on Tethys in a test tank.

Engineers at the institute said this week they've married the best traits of both those AUVs to create a new long-range underwater robot that can travel four times as fast as most traditional gliders, hover in place for weeks at a time, and carry a significant amount of scientific instruments. After four years of development, Tethys underwent real-world testing in Monterey Bay last month, successfully completing a four-day expedition with battery life to spare.

"In designing this AUV, we were actually trying to make a fundamental change in how we do oceanography," said MBARI Chief Technologist Jim Bellingham, who led Tethys' development and explained in a statement how the bot has already been used to track algal blooms.

"Tethys can travel to a spot in the ocean and 'park' there until something interesting happens," he said. "Once a bloom occurs, Tethys can move fast enough to follow the bloom and watch it evolve, the way a biologist on land might follow and study a herd of deer."

Tethys even has some decision-making skills of its own, giving it the ability to direct itself in response to the data it collects. That means the robot can carry on with a continuous expedition 24 hours a day without its human operators dictating its every move. So where traditional AUVs would collect data, send it back to oceanographers, and wait to receive its next set of orders--a process that took up copious valuable time--Tethys can actively follow a bloom as it drifts in the ocean currents.

For now, Tethys is designed specifically to monitor algae, but Bellingham says the hope is to eventually develop other AUVs capable of studying organisms higher up in the food chain.