Hop Rocks is a new location which has been added into the Fortnite map. We are not sure where abouts this will be but we believe it will be in the area that the meteor will have landed. Where that is still remains to be seen.
Here is all the info you need for season 4:
Hop Rocks will let a player float across an area after consuming some of the “glowing rocks which are found around that area. Here is what was found in the mobile store version of Fortnite.
“The comet has left a mark on the island… visit the crater and you’ll find glowing rocks all around. Consume them and lift off with low gravity,”
The game has just been patched and season 4 is now playable and you are free to explore this new area of the map. This addition to the game also shows that the theory about the meteor is actually correct and an area of the map will have been destroyed.
— FortniteINTEL.com • Fortnite news (@FortniteBR) May 1, 2018