Explanation for Lord Byron's poem?

10 Roll on, thou deep and dark blue Ocean – roll!
Ten thousand fleets sweep over thee in vain;
Man marks the earth with ruin – his control
Stops with the shore; upon the watery plain
The wrecks are all thy deed, nor doth remain
15 A shadow of man’s ravage, save his own,
When, for a moment, like a drop of rain,
He sinks into thy depths with bubbling groan,
Without a grave, unknelled, uncoffined, and unknown.
3
And I have loved thee, Ocean! and my joy
20 Of youthful sports was on thy breast

Question

Explanation for Lord Byron's poem?

10	     Roll on, thou deep and dark blue Ocean – roll!
	     Ten thousand fleets sweep over thee in vain;
	     Man marks the earth with ruin – his control
	     Stops with the shore; upon the watery plain
	     The wrecks are all thy deed, nor doth remain
15	     A shadow of man’s ravage, save his own,
	     When, for a moment, like a drop of rain,
	     He sinks into thy depths with bubbling groan,
	Without a grave, unknelled, uncoffined, and unknown.
3
	     And I have loved thee, Ocean! and my joy
20	     Of youthful sports was on thy breast

anonymous · Answer

It seems the poem is a man who has spent his life on the ocean (getting that from the last lines) and he is speaking of the strength, power, and untamed characteristics of the ocean. He talks about how man has changes things on land but they can't change or control the ocean. He also speaks of how the ocean takes lives in shipwrecks and what's left is unseen (because its beneath the water). 

That's what I'm getting from it. If your book has a brief summary of the author, that might also be a clue as to what he is trying to portray through his poems. Some authors say what they mean so it's easily understood and others make it to where there's a deeper meaning than what first meets the eye. Hope I've helped :)