1774, partial loan-translation of Dutch ijsberg, literally "ice mountain," from ijs "ice" (see ice (n.)) + berg "mountain" (see barrow (n.2)). An earlier term was sea-hill (1690s). Phrase tip of the iceberg, in a figurative sense, first recorded 1962. Iceberg lettuce attested from 1893.
1. The above complaints are, I suspect, just the tip of the iceberg.
2. The Titanic met her fate by crashing into a huge iceberg.