The tip of the iceberg Neutral

A small, visible portion of a much larger problem or situation that remains hidden.

It’s used to warn that what has been noticed or revealed so far is only a fraction of the full scale of an issue.

The phrase draws on a real oceanographic fact: because ice is only slightly less dense than seawater, roughly nine-tenths of an iceberg’s mass lies submerged, with only a small fraction visible above the surface — a relationship governed by simple buoyancy (Archimedes’ principle). The idiom’s rise to everyday use owes a great deal to the sinking of the RMS Titanic in 1912: after the collision with an iceberg, the danger posed by an object’s hidden underwater bulk became a matter of intense public discussion, and the ship’s lookouts, famously, had been able to see only the iceberg’s visible tip before the impact. By the mid-20th century, “the tip of the iceberg” had become a standard figure of speech for any problem whose full extent lies mostly out of sight.

The reported losses turned out to be just the tip of the iceberg.

These complaints are only the tip of the iceberg — there are dozens more we haven’t heard yet.

Investigators say the fraud they’ve uncovered so far is only the tip of the iceberg.

A: They found three errors in the report. B: That’s just the tip of the iceberg, trust me.