It is an interesting [natural] phenomenon
Psalm 113
"What ailed thee, O thou sea, that thou didst flee: and thou, O Jordan, that thou wast turned back?"
"Quid est tibi mare quod fugisti et tu Iordanis quia conversus es retrorsum"
I notice on the river which runs through my home town (River Ribble) that at certain times the water appears to run up river. Must be to do with it being tidal.
Next time I see it with a camera handy I'll take some footage.
A youtube video of the Ribble tidal bore:
https://www.youtube.com/watch?v=nooW_Pg3gpw
Is more noticable/impressive further upstream where it can be seen only to be travelling upstream. Not sure it is a bore I have seen...could be different phenomenon all together as the Ribble is pressing against the Irish Sea (part of the Atlantic).
Most famous example in the UK is the River Severn which regularly flows backwards at high tide:
Severn bore