If you’ve never heard of jacquard, it’s just a fancy word for a texture that’s woven into a fabric—which in this case is that stripe pattern. The trick is in keeping the shirt soft while you do it.
An absurdly soft jacquard that Marine Layer really outdid themselves on. Jacquard means that the pattern you see is actually woven into the fabric, not dyed on top. It's a higher-end technique that makes even tee-like fabrics feel extra premium.