Quoted from H. P. Lovecraft's Call of Cthulhu

Poor Johansen’s handwriting almost gave out when he wrote of this. Of the six men who never reached the ship, he thinks two perished of pure fright in that accursed instant. The Thing cannot be described—there is no language for such abysms of shrieking and immemorial lunacy, such eldritch contradictions of all matter, force, and cosmic order. A mountain walked or stumbled. God! What wonder that across the earth a great architect went mad, and poor Wilcox raved with fever in that telepathic instant? The Thing of the idols, the green, sticky spawn of the stars, had awaked to claim his own. The stars were right again, and what an age-old cult had failed to do by design, a band of innocent sailors had done by accident. After vigintillions of years great Cthulhu was loose again, and ravening for delight.
Three men were swept up by the flabby claws before anybody turned. God rest them, if there be any rest in the universe. They were Donovan, Guerrera, and Ångstrom. Parker slipped as the other three were plunging frenziedly over endless vistas of green-crusted rock to the boat, and Johansen swears he was swallowed up by an angle of masonry which shouldn’t have been there; an angle which was acute, but behaved as if it were obtuse. So only Briden and Johansen reached the boat, and pulled desperately for the Alert as the mountainous monstrosity flopped down the slimy stones and hesitated floundering at the edge of the water.
Steam had not been suffered to go down entirely, despite the departure of all hands for the shore; and it was the work of only a few moments of feverish rushing up and down between wheel and engines to get the Alert under way. Slowly, amidst the distorted horrors of that indescribable scene, she began to churn the lethal waters; whilst on the masonry of that charnel shore that was not of earth the titan Thing from the stars slavered and gibbered like Polypheme cursing the fleeing ship of Odysseus. Then, bolder than the storied Cyclops, great Cthulhu slid greasily into the water and began to pursue with vast wave-raising strokes of cosmic potency. Briden looked back and went mad, laughing shrilly as he kept on laughing at intervals till death found him one night in the cabin whilst Johansen was wandering deliriously.
But Johansen had not given out yet. Knowing that the Thing could surely overtake the Alert until steam was fully up, he resolved on a desperate chance; and, setting the engine for full speed, ran lightning-like on deck and reversed the wheel. There was a mighty eddying and foaming in the noisome brine, and as the steam mounted higher and higher the brave Norwegian drove his vessel head on against the pursuing jelly which rose above the unclean froth like the stern of a daemon galleon. The awful squid-head with writhing feelers came nearly up to the bowsprit of the sturdy yacht, but Johansen drove on relentlessly. There was a bursting as of an exploding bladder, a slushy nastiness as of a cloven sunfish, a stench as of a thousand opened graves, and a sound that the chronicler would not put on paper. For an instant the ship was befouled by an acrid and blinding green cloud, and then there was only a venomous seething astern; where—God in heaven!—the scattered plasticity of that nameless sky-spawn was nebulously recombining in its hateful original form, whilst its distance widened every second as the Alert gained impetus from its mounting steam.

this passage was written in a way that, to me, is pure genius. H. P. Lovecraft's description, or lack thereof of this Cthulhu was done so well under the pretense that the thing couldn't be described. he only vaguely hinted at the horror that this creature was and he hinted beautifully with as much detail as possible without actually describing it, leaving it up to the readers imagination. later on in the passage he describes johansens attempt to escape. By smashing the steamboat into Cthulhu's head, the reader then believes that Johansens, and humanity has won. then takes that feeling away and replacing it with utter hopelessness as Cthulhu reforms. The creature cannot be beaten or stopped by the likes of man, this passage says, we are the utterly small hopeless prey of forces far beyond our control.