- We are responsible for getting the oceanographic data in front of Thwaites Glacier, and we do that with totally different means from traditional ship-based measurements.

What we do here is, we tag elephant seals.

I think we should stop at one point.

narrator: Elephant seals are the biggest and deepest diving seal species.

The largest can weigh twice as much as the average car.

[dramatic music] Getting up close takes careful planning.

- If we use a dart, we have to make sure for 10, 15 minutes that this seal is not going into the water, and he seems to like moving.

♪ ♪ [penguins squawking] ♪ ♪ [seal growling] ♪ ♪ - Everybody knows what they have to do?

- Yeah.

- Helping.

I'll get the tracks.

♪ ♪ narrator: The sedated seal is fitted with miniature oceanographic sensors.

♪ ♪ They'll record the location, depth, and water temperature whenever the seal dives.

♪ ♪ - The warm water down here is at depth, so we need something that goes deep in the water, and these seals do that.

narrator: Elephant seals act as living submarines, diving as deep as 5,500 feet and staying under the ice for up to 90 minutes.

♪ ♪ Multiple seals are tagged to create a detailed record of the increasing seawater temperature at the base of Thwaites Glacier.

- This morning, I think we put three tags out, which is a really good day for us.

[laughs] narrator: Highly fashionable, this high-tech headgear will fall off harmlessly after recording a year's worth of vital data.

♪ ♪ - Getting the seals to help us to collect data is really amazing in terms of oceanography.

It gives us a really nice overview of what the ocean does here in front of Thwaites Glacier.

♪ ♪