I did also drown my Colorado 300.
A few days ago on the "Stammtisch Oslo" event I demonstrated my Colorado 300. I wanted to show that it was waterproof, put the Colorado in an empty glass and filled it with water. Oh, yes I was sure the unit was properly closed. After 10 sec someone noticed air bubbles coming from the battery compartment. I pulled out the Colorado but it was too late. The unit was full of water, not only in the battery compartment, but we could also see a few mm water level in the display. Well, my Colorado has a new nickname "bathing duck", and after three days it has began to work again. Time will show if the display will be 100% ok. The biggest surprise was that it seems to be openings between the battery compartment and the electronics. My conclusion is that this unit is not IPX7 waterproof.