[phaer]

I suppose it's less safe then a pool, but I don't think there's more current compared to the Danube and there are boats there as well.

[welder]

Yea, Alte and Neu Donau are safe but Donau and Kanal... I see people do it with a balloon strapped to their waist for visibility to boats, but I wouldn't do it.

Those pontoon ferry boats travel over 30 km/h on the Kanal.