I didn't know you are on holiday.

You can make a post on community worldmappin.

https://worldmappin.com/

Create a normal hive post in the community created/hive-163772 after subscribing.

Get the code from the website, post the code in the place of code entry when you publish from peakd and you are good. You can see all your pin as you travel. It is quite nice.

Terschelling looks like a barrier island. These breaks are called tidal inlets, the ones with red arrows.

Barrier islands are sand dominated in normal times, but since most of the world is currently in a highstand, lot of the barrier islands are muddy, as I can see from your picture. However, if you dig a trench deep enough to go to the time of the last Ice Age, you will see lot of sand :)