In this fifth installment of the popular Mermaids Rock series, which features black-and-white illustrations throughout, Marina and her friends find themselves stranded in a strange jungle when the magic whirlpool malfunctions. How will they get back home?  Join Marina and her mermaid friends in the beautiful coral reef at Mermaids Rock! Whether they're working together to help sea animals in danger or solving a mystery of the deep, there's always an adventure to be had with the best friends of Mermaids Rock. When the magic whirlpool malfunctions, it sends Marina and her friends to a dark, underground river. As they explore the caves and journey along the tunnels, they discover a jungle with amazing wildlife. But then the whirlpool disappears--and they’re stuck! How will they get back home?   Features black-and-white illustrations throughout and informational back matter on cenotes (natural sinkholes) and bats, which Marina encounters in one of the caves.  Join Marina and her mermaid friends in the beautiful coral reef at Mermaids Rock! Whether they're working together to help sea animals in danger or solving a mystery of the deep, there's always an adventure to be had with the best friends of Mermaids Rock.