I'm Rinne. Hello, everyone. :'3

As mentioned in the thread title, I have a question. How would one go about making similar effects to those found along the coastlines of this map, specifically the little dashed lines? I like how it looks and am trying to replicate it in a map I'm currently working on, but I'm not that experienced with Photoshop so I wouldn't know. (I've attached an image as reference.) Thank you in advance!