Part of a New 3-part Pirate Series.

In The Lure of Spanish Gold, Delamare reveals the secret symbiotic relationship between pirates and mermaids.
Who, after all, is more qualified than mermaids to rescue sunken treasure?
Meanwhile, pirates (who similarly live in hiding) are the only humans to which the mermaids regularly reveal themselves.

(copyright warnings are tiny and round monkey seals are absent on actual print)