ESA astronaut Thomas Pesquet waves as he descends to a mockup of the ISS at NASA’s Laboratory in Houston, USA.
Training underwater is as close as it gets to experiencing weightlessness on Earth, so spending time underwater in a full spacesuit is used to practise techniques for spacewalks.
The training pool is the largest indoor swimming pool in the world. It holds over 23 million litres of water! It is still not large enough to hold the complete Space Station, so when astronauts are training, only specific parts of the Station are used.
Divers are on hand to guide the astronauts during their tasks. In space, astronauts are guided by mission control and colleague astronauts on the Station.
A typical training session lasts up to six hours. Imagine spending all that time in a spacesuit 12 metres underwater!
Thomas conducted this spacewalk with his colleague Andreas Mogensen. Watch their slideshow below for more photos, and follow the training on their own blog, which you will find through the link on the right.