Question

Which literary device is used in the comparison between the speaker's experience of fleeing the country and floating in the ocean?
I let myself lie back in deep waters,
my arms out like Jesus’ on his cross,
and instead of sinking down like I’d always done,
magically, that night, I could stay up,
extended metaphor
symbolism
simile
theme'

Answer 1

The answer would be - extended metaphor. It is not a theme, a simile has this schematic form (as red as a lobster), there aren't many symbols here, so this is an extended metaphor, or an allegory. 

Answer 2

the answer is extended metaphor