I found the entire 6 inch chapter for context, and highlighted what I feel is relevant.
To me it's apparent that it is the land that seemed scorching to his feet. The land could only flirt with him but never draw him in, just as it could never lure the ship to its crunchy shores.
Some chapters back, one Bulkington was spoken of, a tall, new-landed
mariner, encountered in New Bedford at the inn.
When on that shivering winter's night, the Pequod thrust her
vindictive bows into the cold malicious waves, who should I see
standing at her helm but Bulkington! I looked with sympathetic awe and
fearfulness upon the man, who in mid-winter just landed from a four
years' dangerous voyage, could so unrestingly push off again for still
another tempestuous term. The land seemed scorching to his feet.
Wonderfullest things are ever the unmentionable; deep memories yield
no epitaphs; this six-inch chapter is the stoneless grave of
Bulkington. Let me only say that it fared with him as with the
storm-tossed ship, that miserably drives along the leeward land. The
port would fain give succor; the port is pitiful; in the port is
safety, comfort, hearthstone, supper, warm blankets, friends, all
that's kind to our mortalities. But in that gale, the port, the land,
is that ship's direst jeopardy; she must fly all hospitality; one
touch of land, though it but graze the keel, would make her shudder
through and through. With all her might she crowds all sail off shore;
in so doing, fights 'gainst the very winds that fain would blow her
homeward; seeks all the lashed sea's landlessness again; for refuge's
sake forlornly rushing into peril; her only friend her bitterest foe!
Know ye, now, Bulkington? Glimpses do ye seem to see of that mortally
intolerable truth; that all deep, earnest thinking is but the intrepid
effort of the soul to keep the open independence of her sea; while the
wildest winds of heaven and earth conspire to cast her on the
treacherous, slavish shore?
But as in landlessness alone resides the highest truth, shoreless,
indefinite as God - so, better is it to perish in that howling
infinite, than be ingloriously dashed upon the lee, even if that were
safety! For worm-like, then, oh! who would craven crawl to land!
Terrors of the terrible! is all this agony so vain? Take heart, take
heart, O Bulkington! Bear thee grimly, demigod! Up from the spray of
thy ocean-perishing - straight up, leaps thy apotheosis!