An underwater glider is a small submarine that’s autonomous–which means there’s nobody inside it, one reason being that nobody could possibly fit in there: it’s only about 2 meters long and weights around 50 kilos.

Underwater gliders are used to observe the seas and the oceans. Scientists place them in the water and the gliders collect interesting data about the temperature, the amount of salt and oxygen in the water, and so forth. They do so by using sensors that measure that information and much more (depth, etc.)


Imagen interactivoImagen interactivo
BATTERIES They can be lithium or alkaline batteries, and provide power for the glider. The batteries also move back and forth inside the glider. If they move forward, they help it sink. If they move backward, they help it go up.
NAVIGATION BAY This is the part of the processor in charge of the glider's navigation device.
PISTON It fills up and releases water, making the glider dive down or come up. When it fills up, down goes the glider. When it empties out, that space fills up with air and makes the glider float to the surface.
SCIENCE BAY This is the part of the processor in charge of the scientific sensors.


  • Gliders use their “wings” to glide along in the sea. They’re like airplanes, only in the water!
  • They use very little energy because they glide; they don’t have any motors or propellors.
  • They can dive as deep as 1000 meters.
  • They can go as fast as 10-20 centimeters per second in vertical motion, but if the currents help them along, they can go up to 1 kilometer an hour.
  • They can send data to the lab through their antennas, and receive data, too.


There are other ways of getting data about the sea. One of them is organizing an expedition with several scientists, hopping on a boat, and sailing off for a few days, weeks, or even months to take all kinds of measurements. What are the advantages and disadvantages of using underwater gliders instead of other systems like boats?

  • They work 24 hours a day, 7 days a week.
  • They cover large distances.
  • They can go on long-term missions.
  • They're autonomous, unmanned systems, so you don't need a large number of people on board, as you would on a boat. Therefore, they're much cheaper!
  • They can include many different sensors to measure many kinds of data (temperature, salinity, chlorophyll, oxygen... even sounds!)
  • They allow us to collect almost real-time data.
  • They move very slowly.
  • They can only go down 1000 meters. They can't go any deeper!
  • They can't take samples on the spot. They don't have an arm that can take sand or water samples, for example. They can only collect data!
  • Their sensors are still quite low-resolution compared to the ones available on boats.
  • Their technology is very recent. They're still in the prototype stage, so things don't always work properly.
  • Watch out! Danger! They can run into fishing nets, plastic objects, or collide with the sea floor or boats.