Dracco
+ :)
I agree about the Nagas on turtles; I only see them on land. They don't really complement each other underwater. The Naga is agile.

...At sunset, majestic riders began to emerge from the restless sea onto the sandy shore. Huge, yet obedient, Turtles moved purposefully towards the "land rats." Sunlight glinted on their wet shells, and the Nagas gazed longingly at the water.
Hours passed, and the Nagas continued to leave the cool substance without which their lives would not exist.
By some imperceptible, subconscious signal, the entire horde of warriors froze. Only the settling sand, disturbed by their movement, and the noisy ocean broke the silence. The Nagas listened to this monotonous, soothing sound of their home. The sea seemed to play farewell music for its inhabitants. And every single warrior understood that ahead of them lay a hot, hard, and much-disliked land.
Wars and alliances await them, as well as death and feats...
But there is one big BUT: the Nagas had a goal. Is that too grand a statement? Not at all. They had a Great Goal, and everything was at stake. Defeat was not even an option, because the enemy is merciless, and the servants of the sea will respond in kind...

I wanted to convey a bit of atmosphere. Something similar could be used as an introduction to a story about the Nagas, and then developed further.