Snowflake and the Lost City of Ice

When Snowflake visits her old pal M.T. Present, the ex-adventurer reveals that there may be more under the forgotten half-frozen lake than meets the eye...
Somewhere under Christmas Island lies an underwater city completely hidden from sight by ancient magic. Legend says the Hidden Kingdom is home to a unique type of Reindeer, along with a mysterious treasure called the Crown of Crystalaqua.
As soon as she learns about it, Snowflake can't get her head out of the water. She has to see it. But how?
Many dangers await those who try to enter the forbidden city of Crystalaqua.
Can the brave adventurer find the secret city under the lake, even if it means swimming blind?

Thanks to A.K. Yearling for the inspiration from reading Daring Do as a child