Pencil grid, pencil & black biro line work.
Black biro line work with watercolor shading added.
With the black scriveners ink added.
I'm really surprised with how well the underwater parts turned out in the photo of the painting. For a split second I thought I'd uploaded the wrong image until I noticed the splodgy reflections in the background. When I look at the actual painting I can't help but see biro squiggles!