Survival at Sea: The Supporting Actress is Lucky.

After accidentally falling off a cliff and being transported into a male-oriented sea survival novel she'd read, Ye Yufei doesn't want to become the cannon fodder of the same title, and she also wants her brother to be alive and well. She wants to complete this sea survival game and get out of this game world alive. (Main quest - sea raft survival, side quest - various dungeons)