Here's what rhymes with seasnail.
male mail nail snail scale fail sale pale sail tail tale jail rail veil frail gale hail shale whale bail email stale vale wail bale dale pail flail hale kale faille wale trail avail entail assail inhale quail quale braille unveil grail impale hightail detail curtail exhale bewail derail gunwale mainsail pigtail foresail monorail taffrail wassail pellmell hangnail carrell prevail travail fingernail ponytail topsail bobtail lugsail countervail martingale nonpareil swallowtail tattletale