Out of a fired ship, which by no way
But drowning could be rescued from the flame,
Some men leap'd forth, and ever as they came
Near the foes' ships, did by their shot decay;
So all were lost, which in the ship were found,
Donne begins this poem by setting the scene on a ship. The ship has come under attack, and is on fire. The only way the men could escape the fire on the ship is to drown in the water. 
 This beginning starts to talk about life and death, and the choice between which way one could die, death it a common theme for Donne.
A Burnt Ship