Historical clue formulations

• Like Crater Lake, compared to any other U.S. lake — 2021-05-02
• Like the diving end of a pool vis-à-vis the other end — 2014-07-29
• Further in — 2012-03-01
• More profound — 2008-11-10
• More profound — 2008-04-07
• More profound — 2005-11-21
• Having more bass — 2004-06-18
• Like Ontario vis-à-vis Erie — 2000-01-08