Sri Lanka's seaplanes move with the monsoon
The domestic air network swaps coasts twice a year, landing on tea-country reservoirs. The three routes where the fare is worth it. Cinnamon Air flies eight-seat amphibious Cessnas that land on water, which is how it reaches Castlereagh Reservoir in the tea estates and Koggala Lagoon behind the south coast beaches, places that have no runway and never.
The practical picture
Cinnamon Air flies eight-seat amphibious Cessnas that land on water, which is how it reaches Castlereagh Reservoir in the tea estates and Koggala Lagoon behind the south coast beaches, places that have no runway and never will. The entire scheduled network relocates seasonally: the east coast to Trincomalee and Batticaloa from 1 May to 31 October, then the south coast and hill country from 1 November to 30 April. The route you read about may not exist on your dates.
It is worth the money on three routes. Colombo to Trincomalee in summer, 45 minutes against five to six hours by road. Colombo to Jaffna year round on FitsAir from Ratmalana, under an hour against seven to eight. And Colombo to Castlereagh or Kandy in winter, thirty minutes instead of four hours of hairpins. It is not worth it to the south coast, where the expressway does Colombo to Galle in under two hours. Never book one as a same-day connection to an international flight: these are daylight-only aircraft and weather cancels them often.
Frequently asked
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Sources
We compile and link to public sources; details change, so verify time-sensitive specifics before you travel.