Possible Clues:

• Place having submerged tin works appearing in map
• Fabled lost island
• Finally changing direction, one's found a vanished land
• Legendary vanished island
• Lack of religion made this city go into liquidation
• 2001 Disney film subtitled "The Lost Empire"
• Titan carrying collection of books — one is "The Lost Continent"
• Merry at last in idyllic island
• This is "way down below the ocean, where I want to be"
• What sank Liberal opposition after a time?