Always through blinding cables, to our joy,
Of thy white seizure springs the prophecy:
Always through spiring cordage, pyramids
Of silver sequel, Deity's young name
Kinetic of white choiring wings . . . ascends.
Migrations that must needs void memory,
Inventions that cobblestone the heart,—
Unspeakable Thou Bridge to Thee, O Love.
Thy pardon for this history, whitest Flower,
O Answerer of all,—Anemone,—
Now while thy petals spend the suns about us, hold—
(O Thou whose radiance doth inherit me)
Atlantis,—hold thy floating singer late!
So to thine Everpresence, beyond time,
Like spears ensanguined of one tolling star
That bleeds infinity—the orphic strings,
The implication here is that the poet is sinking and singing as he desperately tries to stay afloat. Perhaps an oblique reference to Crane’s personal troubles: he was a severe alcoholic only a few years away from suicide. 
 Perhaps also a reference to  Matthew 14:28-31,  in which Jesus tells Peter to walk on water: 
 
 Matthew 14:28 And Peter answered him and said, Lord, if it be thou, bid me come unto thee on the water. 
 Matthew 14:29: And he said, Come. And when Peter was come down out of the ship, he walked on the water, to go to Jesus. 
 Matthew 14:30: But when he saw the wind boisterous, he was afraid; and beginning to sink, he cried, saying, Lord, save me. 
 Matthew 14:31: And immediately Jesus stretched forth his hand, and caught him, and said unto him, O thou of little faith, wherefore didst thou doubt? 
 
 Crane may be struggling with doubt, pleading for the strength to keep faith with his art (his “singing”). 
 Compare also Bob Dylan in  “A Hard Rain’s A-Gonna Fall”  (1962): 
 Then I’ll stand on the ocean until I start sinking But I’ll know my song well before I start singing
Atlantis