If we can imagine a horse having two or three explosive spears stuck into its stomach and being made to pull a butcher’s truck through the streets of London while it pours blood in the gutter, we shall have an idea of the present method of killing. The gunners themselves admit that if whales could scream, the industry would stop, for nobody would be able to stand it.”
Today, whale hunters use these same methods, with exploding harpoons to catch and haul whales in and high-powered rifles to finish them off. Even this, however, does not capture the violence of a whale hunt.

Consider:

Whales are often pursued to the point of exhaustion before they are harpooned.

Wounded, harpooned whales are dragged to whaling vessels, where they may be speared with more harpoons or shot with high-powered rifles. Whales which are harpooned near the tail and then winched in alive to the bow of the catcher ship eventually die of suffocation as their heads are forced underwater.
Because whales are able to slow their breathing and heart rate, many that appear dead or unconscious are probably still feeling extreme pain.