Answer:
Large as a mountain, small as a pea, Endlessly swimming in a water-less sea.
Gold in a leather bag, swinging on a tree, money after honey in its time. Ills of a scurvy crew cured by the sea, reason in its season but no rhyme.
What has a single eye but cannot see?
Walk on the living, they don’t even mumble, Walk on the dead, they mutter and grumble. What are they?
They can be harbored, but few hold water. You can nurse them, but only by holding them against someone else. You can carry them, but not with your arms. You can bury them, but not in the earth.
If it’s information you seek, come and see me. If it’s pairs of letters you need, I have consecutively three. What am I?