Here is the sentence:
Dangling his legs over the water, Tommy sat
on the pier and cried. Infused with his great sadness, the tears hit the
waves and attracted Marina, a beautiful mermaid. Popping out of the ocean
as sleek as a seal, Tommy gasped at the sight. While Marina’s tail flopped
against the wood, which was long, scaly, and metallic blue, she asked poor
Tommy the reason for his pain. Tommy explained that he had lost the surfing
championship, which included a scholarship to college. Assessing his set
as clumsy and inelegant, not a single compliment was received from the judges.
After Tommy bemoaned his ineptitude on a surfboard,
Marina made a proposal: She would turn him into a merman with the grace
and athleticism of a dolphin! Wielding
ancient ocean secrets with a snap of her fingers, a metallic green tail
replaced Tommy’s legs! Diving into the waves, the tail propelled Tommy through
the strong surf. Ecstatic about his new abilities, the training and advice
Marina offered went unheeded. Refusing to use conditioner, for example,
the sun and salt water soon damaged Tommy’s hair, which became dry and brittle.
A dangerous and foolhardy activity, Tommy also insisted on head bumping
the Great White sharks that he encountered. Putting straws up his nose and
barking like a walrus did not make Tommy popular when he had dinner with
Neptune, Marina’s father. After thoughtlessly scrambling endangered sea
turtle eggs for breakfast, an apology had to be made not only to Marina
but also to the grieving reptile mother. One day out on a swim, Tommy drank
a root beer and tossed the empty plastic bottle in the water. Polluting
the ocean so carelessly was the last clam shell for Marina. With an angry
snap of her fingers, she replaced Tommy’s tail with two human legs. Sinking
under the waves, Tommy’s legs finally kicked him to the surface where he
gulped a much needed breath of air. Saying a curt goodbye, Marina’s tail
slapped the surface dismissively as she dove into the ocean depths. While
swimming the mile back to shore as a regular human being, Tommy regretted
the gift that he had squandered.
In this sentence, no phrases are misplaced or dangling. Every clause has a clear subject for its verb. Good job!