On Shabbat, we are forbidden to carry or transport objects in a "public domain," unless it is surrounded by walls or an eruv. Skateboarding in a public domain is hence forbidden, as it is a mode of transporting the skateboard.

A second issue which should possibly be considered: According to Jewish law, the restful atmosphere of Shabbat is intended to permeate all the day's activities. To the extent that "your manner of walking on Shabbat should be different than your walking during the weekdays."1 On Shabbat our walking assumes a refined, relaxed and comfortable pace—the rat-race of the week past and the week ahead completely out of mind. We don't run or walk hurriedly. Thus skateboarding might also be a violation of the Shabbat spirit (even within the confines of a "private domain").

Yours truly,

Rabbi Menachem Posner