How can I make a path in a map walkable?

[tikztikz]

I'm trying to make a macro of this course, and the problem is that kore can't walk through the water. I'm thinking of editing the .rsw or .gat file but I have no clue how to do it.

[noobotter]

Even though you edit that part in the gat/rsw files, as long as the mapcache in the server doesn't have a walkable area in that part, it's still useless.
You can edit using Browedit, check the eAthena forums or rAthena forums.