[jamal-kumar]

https://www.youtube.com/watch?v=wAFYVpX45xs

Here's a video of what it looks like from the 2011 event, from the POV of the coast guard approaching it. Waves don't typically look like a sheet has been flapped across one front of the entire horizon of what is visible on the ocean

[ninetyninenine]

Yeah that's a wave bro. Notice how the ocean rises above it's own typical sea level? That's not water "filling in a gap" the way tides do it as sea level changes.

That's a huge ass wave as it's a pulse traveling on top of the ocean, above sea level.

[AshleyGrant]

That's what it is like out at sea. There's a reason tsunamis are referred to as "tidal waves." For example, watch this video of a tsunami hitting a port today: https://www.youtube.com/watch?v=M1B1J6sgFxk