Historical clue formulations

• 1960s underwater habitat — 2017-05-10
• Aquanaut's workplace — 2015-07-14
• Old Navy work site — 2014-11-02
• Man-made habitat — 2011-07-16
• Experimental underwater habitat — 2007-06-17
• Aquanaut's workplace — 2003-08-16
• Aquanaut's base — 1999-11-14
• Aquanaut's place — 1999-08-01
• Test site for an aquanaut — 1998-12-18
• Underwater experiment site — 1998-05-05