Definition of "reefy"

I sit up to see myself safe through the narrow passage between Flat Island and Round Island, and fall asleep at last to the monotonous chant of so many "fathoms and no bottom," for we take soundings every five minutes or so in this reefy region.

1878, Various, Lippincott's Magazine of Popular Literature and Science, Volume 22. October, 1878.‎

The land here is high, hilly, and reefy near the sandy beach; seeing that nothing profitable could be effected here, we returned to the yacht, which was lying-by under small sail; towards the evening we were at about 1 mile's distance from three islets, of which the southernmost was the largest; five miles by estimation farther to northward we saw a mountainous country, but the shallows rendered (or render) it impossible for us to get near it; in almost every direction in which soundings were taken, we found very shallow water, so that we sailed for a long time in 5, 4, 3, 21/2, 2, 11/2 fathom and even less, so that at last we were forced to drop anchor in 11/2 fathom, without knowing where to look for greater or less depths; after sunset we therefore sent out the pinnace to take soundings, which found deeper water a long way S.W. of the pinnace, viz. 2, 3, and 41/2 fathom; we were very glad to sail thither with the yacht, and cast anchor in 81/2 fathom, fervently thanking God Almighty for his inexpressible mercy and clemency, shown us in this emergency as in all others.

1899, J. E. Heeres, The Part Borne by the Dutch in the Discovery of Australia 1606-1765‎

Then the water clears and his sails swing to the wind, and he is off to the north, along that steel-gray shore of rampart rock, between the white-slab islands and the reefy coast.

1909, Agnes C. Laut, Canada= the Empire of the North‎