Slipping on ice

Last week I was on a personal tour and walked a bit on snow mountains. I saw water flowing down under ice and some of the tourists are sliding from heights on a sledge nearby. There were no barricades to prevent accidental fall into flowing water from ice melting, ending up under ice in-between and resurfacing at distance away. If any anybody looses control during sliding/skating, he/she may not be alive as it is likely that the passage under the ice is not big enough to allow onto the other end and one can not climb back as the water is flowing at great force. This is first time I went to snow mountains and is a lesson for me.