President Kersti Kaljulaid met with polar scientists and learnt about the life of penguins during her visit to Antarctica.
Kaljulaid wrote on social media on Friday that she had met with scientists from Uraguay and South Korea and had been told the speed of climate change was affecting their work.
The Facebook message said: "We got to know the life of the Antarctic people, both humans and animals, between the ice and the rock. The research here is something that can only be done here on the continent - because of the speed of climate change. The commitment of the scientists here is impressive."
The president visited Crescent Island, where she watched a colony of harlequin penguins, and Deception Island, part of the South Shetland Archipelago, where the Bellingshausen voyage landed 200 years ago.
The head of the Uruguayan Polar Station gave Kaljulaid and her team a tour of their station's history and ongoing research. "Uruguay, like us, is a small country, and their station is relatively simple and modest. Because of its location, a lot of marine research is done. We talked primarily about marine biology," Kaljulaid wrote.
On another visit to the South Korean-led research station, King Sejong, the Estonians were greeted with blue, black and white flags.
Editor: Helen Wright