I’ve heard that spawning salmon travel up stream on their way back from the ocean. They go up waterfalls while they

Question: I've heard that spawning salmon travel up stream on their way back from the ocean. They go up waterfalls while they swim. How is this possible?
- Keywords:
  fish,
  salmon,
  waterfall
Asked by to Aimee, Chris, Dave, Greig, Laurence on 17 Jun 2014. This question was also asked by .
- Dave Jones answered on 17 Jun 2014:
  
  I don’t think they manage to go up really big waterfalls, like Niagara Falls or something like that. But, Salmon are really powerful and can jump pretty high (just like dolphins can jump out the water), so they can go up small waterfalls by swimming really fast and then jumping as hard as they can!
- Laurence Perreault Levasseur answered on 17 Jun 2014:
  
  They are amazing athletes! Actually they can climb pretty tall waterfalls by constantly jumping out of the fall against the current. Maybe not the Niagara falls, but pretty impressive fall regardless! I’ll try to find a video!
  
  Edit:
  photo:
  
  video of salmons climbing a relatively small fall:
  
  Salmons usually cannot jump over things like electric dams, and so special passes have to be build for them to go through up the river.
- Greig Cowan answered on 25 Jun 2014:
  
  Salmon are quite impressive! Although the water is travelling quickly downstream, as long as the salmon can swim faster upstream, then they will be able to move forward. It’s all about their speed relative to that of the water.

Question: I've heard that spawning salmon travel up stream on their way back from the ocean. They go up waterfalls while they swim. How is this possible?