Chola runs the strongest trade-into-navy pipeline of the Exploration Age — every active Trade Route makes your fleet stronger, turning a peaceful economic game into a genuine naval deterrent almost by accident.
"Samayam" grants an additional Trade Route from Trade Agreements, plus increased Gold and Influence for every active Trade Route and increased Movement for Merchants. Its Exploration Age Apex tier adds increased Combat Strength for Naval Units for every other civilization you have a Trade Route with, plus increased Movement and Sight for Heavy Naval Units — a genuinely unusual mechanic that converts peaceful trade directly into military strength.
The Kalam is a unique Naval unit that gets an additional Attack per turn when Movement allows. The Ottru is a unique Naval Commander that reduces the Combat Strength of opposing units within its command radius, making it a strong deterrent even without firing a shot.
Chola's unique buildings are the Manigramam (Happiness, plus Gold adjacency for Quarters and Wonders, Ageless, must be placed adjacent to Coast) and the Anjuvannam (Gold, plus adjacency for Coastal terrain and Navigable Rivers, and increased Production toward Naval units), combining into the Five Hundred Lords Unique Quarter which extends both Land and Water Trade Route range. The associated Wonder, the Brihadeeswarar Temple, must be built on or adjacent to a Navigable River.