Why it matters
A 2001 sonar survey off western Cuba showed symmetrical shapes ~650 m deep — too deep for any recent human site, which is exactly why it stays unconfirmed and haunting.
What mainstream says
A single sonar pass, never re-imaged or ground-truthed; the depth makes a human origin implausible on known timescales. Grade: speculation.
Graded Speculation · S on the Ancient Code honesty scale (A grounded · C contested · S speculation · U unidentified). It belongs to the Drowned worlds line of evidence.
Sources & further reading
The authoritative reference for this site/finding — and its own primary citations — so you can check us.