I drug a copy of the photo onto Google and it identified it as a Pintado petrel. I take a lot of bird photos and when I get one that I don’t know I drag and drop a copy of the photo onto Google search box. It is always good to check it with other photos to confirm things. Hope this helps.
The iNaturalist website https://www.inaturalist.org/ also gives a preliminary ID of Pintado Petrel. If you post the observation there, other users will help ID the bird.