Possible Clues:

• World's largest lake
• Largest lake in the world
• Prince standing on his head, say, in lake
• There's lots of water here, in case a spa needs a change
• Largest salt lake in the world
• Swimming space, as in a large expanse of water
• Asian space, very fluid
• Lake bordered by both Russia and Iran
• Body of water, fluid Asian 2?
• The Volga River flows into it