Swiss windsurfer Balz Müller has been chasing winter storms for quite a while, but what you're about to witness is absolutely extreme.
On December 11, Switzerland's Lake Uri was invaded by a dry, warm, and down-slope wind called foehn wind, resulting in powerful 120 km/h (75 mph) winds.
Müller and a small group of local windsurfers decided to give it a go.
A decade ago, the 23-year-old sailor watched a video shot in Pointe Rouge, Marseille, and dreamed of riding a similar storm. So, this was his day.
"Traditionally, the foehn wind needs about 4hPa difference between the south and north of the Swiss Alps to break through the alpine valleys. That day, we had over 18 hPa difference," explained Balz Müller.
"The southerly foehn wind was blowing extreme gale-force gusts of over 120 km/h."
"It's been three years since I last used my 3.3 sail, but this time I had no choice with winds up to 65 knots. What an adventure! Have you ever wondered how much wind is still sailable?"
Watch how Balz Müller and friends battle the choppy waters, wind swells, and flying pieces of trees, leaves, and bushes.
Lake Uri (Urnersee) is the southeastern arm of Lake Lucerne.