How do I catch the scenic sea train from Colombo Fort?

You should take any train heading toward Galle, Matara, or Kalutara. These usually depart from platforms 4 or 5 at Colombo Fort. Try to catch an afternoon train around 4:30 PM to see the sunset over the ocean. Make sure to sit on the right side of the carriage when heading south to get that iconic view where the tracks are just meters away from the water.