Physeter.

"A geyser of blood spraying out..."

Why do you persist?
Why do you and your ilk insist on hunting me as if I were some prize to be gained?
It does not matter how far I swim, for I tire and your wooden beasts are able to make the distance. Nor does it matter how deep I swim, though I can reach depths far beyond you or any of your kin, in time I must return to the surface for a gulp of air; and that's when you strike.
Your fleet encircles me as sharks would, the vessels' paths converging towards one position; mine.
Some of them possess a bulk as great as mine, with great masts stretching upwards into the sky, armed to the greatest extent, whereas beside them, the most foolish of men row straight towards me, even though they are dwarfed by my size.

Weakened from fatigue, I cannot prevent the onslaught about to occur.
Gunshots fill the air, bullets thudding into the sea and into me, leaving little pockmarks where they embedded themselves. The loud roar of a cannon overshadows all for a moment, before its deliverance falls wayward, striking the water several feet to my side.
Positioning yourself to my side, your men stand upon the railings; some in awe at what they chase, others growing wary and hesitant. Even so, you let out a cry, and the men attack. Teeth of steel bite into my flesh, and though they may be little wounds, blood still sprays and I still scream in agony. Lashing out, my tail smacks straight into the side of your ship, sending splinters of wood flying in all directions, crippling your vessel.
Your men panic, but still they shout, still they dig their steel into my back, and still they cut my blubber.
Writhing, I dislodge few, but the damage is already done - somehow, I wriggle out, only to be stopped by a painful sensation in my back. Looking back with dim vision, I can only make out several tendrils buried in me and leading straight back to your ship.

Clever; you've kept me in place and prevented me from leaving - or so you think.
Once more, my fluke is a hammer, smacking upon your vessel, cracking and splintering wood, letting the ocean pour in and drown you and all those by your side. Again
and again
and again
I continue.
Until, at last, your vessel is no more than dead weight by my side, the pieces crumbling as they sink into the depths. The ropes fray and one by one, they break, freeing me from your vice.
I feel your ship sinking down, slowly but surely swallowed by the hungry ocean
Swimming free, I turn. I cannot dive, I am too weak, too tired, too drained to move as quickly as I would want.
Cannot think
Mind muddled - and then it was too late.
I am surrounded - I try to dive down, but the pain is too much. From within, my organs bleed, and the effect that has is very noticeable. Slowing to a crawl, I breathe out, a geyser of blood spraying out onto the water, spreading further out as the seconds pass by.

And now my eyes close. Before I sleep, I can feel the blades once more cutting into my flesh, cutting out chunks of meat and blubber. My oil you burn; even as it slicks the floors of your ships, your fire consumes the last drops, and that which is not burnt, you take for your people.
My vision dims. My jaw hangs without vigour. I choke on the blood that once flew through my veins.
Pumping out blood by the gallons, my heart falters and sputters for the last few seconds of my life, until at last it gives up the fight, and I am no more.

Watching from the depths, a lone whale watches its mother drift listlessly on the waves, torn into by small silhouettes distorted by the light.
Falling back into the darkness, the watcher looks once more before turning away, now alone in the midnight ocean.

Source of whale image: http://www.antiquemapsandprints.com/books/WHALING-BULLEN-1899.htm