Definition of "oilberg"

With the advent of supertankers — aptly nicknamed "oilbergs" — the danger increases that 300,000 tons or more may be dumped in a single mishap.

1970, LIFE, volume 68, number 8, page 29

That is a lot of ship, about the the[sic] size of big tankers before they grew so rapidly to become supers, mammoths and oilbergs.

1973, Jeffrey Potter, Disaster by Oil, page 46