Tidal Wave

When the tide runs out on the Back River it leaves a crust of ice.  When the tide returns you can see the tidal wave as the water rises up hill to our spot.  We are four or five feet above sea level so we get only a 6 foot high tide, rather than the 11 foot downstream.  You can see the tidal wave slipping in over the  frozen river bed. -gwc

The leading edge of the tidal wave which reaches us at half tide.
Three hours later the water will be six feet deep.  The river goes from a 1 foot wide
rivulet at low tide to fifty yards wide at high tide.

Susie Goodall rescued in southern ocean ~ Guardian

https://www.theguardian.com/sport/2018/dec/07/solo-yachtswoman-awaits-cargo-ship-rescue-amid-poor-weather