It was 7am on Wednesday May 2 when Bromeis tried to wade into Toma Lake, Switzerland, where the Rhine's source lies at an altitude of 2,344 metres. Unable to swim in the frozen water, he plunged into a small pool carved into the ice for the occasion.
While he could not begin there, this was used to symbolise the beginning of the 43-year-old Swiss man's aquatic adventure – one that will see him swim through six countries, including Germany, before finally reaching the North Sea a month later.
After skiing down to a nearby Swiss village where the ice had melted, Bromeis took the plunge into four-degree-Celsius water, thus starting his journey for real.
“I'm nervous,” the experienced swimmer told The Local the day before he started his journey. “I really want to make it to Rotterdam, and not die on the way.”
“The Blue Wonder – Rhine 2012” is both a promotional project between Bromeis and the Swiss tourist board and a personal challenge for the former teacher and Olympic triathlon trainer, who is also keen to raise awareness for water-scarcity issues.
He will be swimming between five and six hours a day, covering an average of 50 kilometres depending on the current, how fast the water flows, and what the weather is like.
Chilly water is just one of the hurdles Bromeis is facing. In the first stretch, where the river traverses a 20-kilometre canyon, he will have to be careful not to smash into the rocks that dot the rapids.
At Lake Constance, which is non-flowing, he will have to swim a stretch of 12 kilometres without a current to push him along. But beforehand in Basel, the river runs at a speedy 10 to 15 kilometres per hour.
Anyone imagining him diving down Europe's largest waterfall – the Rhine Falls – will be disappointed though, as he will he will briefly hop ashore before resuming his adventure at the bottom.
And despite being escorted along the way by a small boat with a rescue team, Bromeis is concerned about swimming near the port of Rotterdam, as “the ships there are so big and I am so small.”
He completed a similar challenge in 2008, crossing the 200 lakes of his home canton Graubünden, most of them in glacial temperatures. Two years later, he challenged himself again to swim across the largest lake in each of Switzerland's 26 cantons, covering a total of 300 kilometres.
“My motivation comes from deep inside,” he said, adding that “great passion” for environmental issues pushes him towards his goals.
“Water means life in the whole world,” he said. “We in Switzerland are so privileged to have such a wonderful resource, but we have to be careful because the Rhine is also very fragile and its water is limited.”
Over 50 million people live along the Rhine and through his project Bromeis hopes to inform at least a few of them that the river is not something that should be taken for granted. Along his journey, due to end at the beginning of June, there will be events on the banks for onlookers to show support.