Stock image converted to grayscale, bumped up contrast and bitmapped, combined with surfer silhouette- traced in Illustrator from another stock image. Waves scanned from a surfing magazine, contrasted and otherwise manipulated in Photoshop. I don't suppose I could retrace my steps if I had to, but that's the gist of how this evolved. Now, how to translate to a t-shirt?
Same basic technique here. (RI highlighted for the Rhode Island surf crowd)