Historical clue formulations

• Ocean-mapping instruments — 2026-06-26
• Echolocation systems — 2026-05-16
• They make waves in the ocean — 2020-05-15
• They make waves in the ocean — 2017-06-08
• Sub systems — 2008-05-25
• Finding things? — 2007-03-24
• Submarine detection systems — 2002-01-07
• Submarine detection systems — 1996-08-05