Just an hour's drive from Colombo, the mangroves of the scenic Madu River are waiting to be explored. From there, you can also continue on to Galle to find turtle hatcheries and the Galle Dutch Fort, a 17th century UNESCO heritage site. Stop for lunch by the beach, and watch the local stilt fisherman casting their nets.
Four hours from Colombo you'll find Kandy, the last kingdom of Sri Lanka. The Temple of the Tooth, built in 1595, is centred around the canine tooth of Buddha is a must-visit. Be sure to stop by the Spice Garden in Mawanella or the Tea Factory in Giragama on the way for a glimpse into local industry.
Sri Lanka is also well known for its soft, sandy beaches. Check out the south coast for a relaxing and scenic break.