What does "raise" mean here?

Here's some lines from Bilbo's Last Song by J. R. R. Tolkien
...
Farewell, friends! The sails are set,
the wind is east, the moorings fret.
Shadows long before me lie,
beneath the ever-bending sky,
but islands lie behind the Sun
that I shall raise ere all is done;
...

The last line says "that I shall raise ere all is done", but what shall he "raise"? Would it mean he shall raise "that"(the sun or the island in the previous line), or raise himself, from the bed? I checked every dictionary for the definition of "raise", still can't make sense of it. I really enjoy reading JRRT's Middle-earth, often my poor English won't help though:(

Thanks in advance.