Airline pilot here…

Not sure where you were or going…. That being said, there are PACOTS routes that airlines use to cross the Pacific. OCEANIC for the Atantic. WATRS for Western Atlantic. While on these routes, VHF radio doesn’t work so we use HF radio. There is also no radar coverage for most of the journey. So unlike when over the States where we can ask air traffic control for deviations around weather, we have to use something called SLOP (strategic lateral offset procedure). Basically we are allowed to offset the assigned track a certain set of miles as long as we rejoin the track by the last fix on the route. This enables aircraft to fly a route and make its own deviations without interfering with other aircraft while not in radar coverage. And if we deviate a certain distance, usually 5miles, we then have to climb or descend a few hundred feet (depending on direction of flight) to as ensure both vertical and lateral separation from aircraft on the same track. Based on that photo and you saying you were crossing the ocean, I’d bet your pilots were performing SLOP to avoid possible weather ahead.

You can read about it here. Probably better explained than what I typed out.

https://en.wikipedia.org/wiki/Strategic_lateral_offset_procedure