In 1990, scientists released uranin 15 metres deep in Switzerland’s Lake Alpnach to track mixing; the dye cloud stretched into an elongated streak as currents moved it

A container with the fluorescent dye was placed on Lake Alpnach, a 4.5 - 4.8 km² basin of Lake Lucerne in central Switzerland, by Swiss scientists in 1990 as part of a series of tracer experiments later reported in the Journal of Geophysical Research. They released between 0.2 and 2 kg of uranin at depths of 15–25 m below the surface.

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