topmost

ylin, ylempi at At or near nearest to the top; uppermost; being the very highest.
2015, Seth Giolle, https://books.google.com/books?id=mkDPCgAAQBAJ&pg=PT227&dq=%22more+topmost%22&hl=en&sa=X&ved=0ahUKEwi4g7Gt6N7PAhVhs1QKHXGQBqcQ6AEIJzACv=onepage&q=%22more%20topmost%22&f=false The Cane Stories

While he worked to ply fingers back apart more than not, Kaiselan practised his crouch exploring the outpost's more topmost levels.