The Ground Markers plugin allows user to mark tiles around the world. Marking tiles can be done by holding the shift key and right clicking the tile you want to mark and then click "Mark tile" in the menu.
You are able to do the following with a marked tile in that same shift right click menu:
The plugin also remembers which tiles you have marked between sessions.
Controls how thick the border of the tiles are.
Displays the marked tiles on the minimap.
Makes marked tiles darker. 0 (fully transparent) - 255 (fully opaque).
Show these menu options when right-clicking the world map orb by the minimap.
The color of the ground markers. Supports transparency.
Right-click the World Map orb by the minimap to import or export ground markers. Importing will check your system clipboard for a ground marker import string. Exporting will copy the ground markers in the area around you to the system clipboard.
Ground marker import strings look like this: [{"regionId":12850,"regionX":22,"regionY":19,"z":0,"color":"#FF000000"},{"regionId":12850,"regionX":21,"regionY":19,"z":0,"color":"#FFDC8700"}]
.
To export all tile markers, sign in to RuneLite and enable cloud sync on the profile that has the tile markers, then visit https://runelite.net/account/tile-markers and click "Export Tile markers".