OK, how about this, it was the plot for one of the best and most fun modules I ever ran, titled "Chariots of Water".
Two countries are at war. One country is loosing, and decides to transport their "Chariot of Victory" to a safe place, as it is prophecied that loosing it would bring about their defeat. The enemy hears of this, and mounts an attack with their own fleet.
Sound good so far...that's just the beginning.
The ship with the chariot is sunk, and the chariot lost. The adventuring team is hired to recover it, and magically transformed into aquatic creatures for this mission (humans = mermen or triton; elves & half-elves = sea elves; dwarves, halflings & gnomes = selkies). They discover that the ship has been looted and the chariot taken by Melenti (Sahuagin/Sea Elf hybrids).
They arrive at the Melenti city, and the group discovers that these creatures are not evil. The history of the city is that it was founded centuries ago by escaped Melenti slaves who had overthrown their Sahuagin masters. They make their living by finding and reselling items from ship wrecks. Their major past time is underwater racing, using sea sleds pulled by domesticated aquatic creatures. The Melenti King wishes to keep the chariot to use in the races. The party agree to a challenge race, the winner keeping the chariot plus other treasure that the party puts up.
What follows is an underwater version of the race from Ben Hur. I had expected that once the party got their hands on the chariot they would just try to escape with it, but they instead decide to play the game out honorably and fairly. The party barely wins the race. They then negotiate future trade agreements with the Melenti, and all sides end as winners.