Hey, Top things to do in Srilanka, 1) Gangaramaya temple in Colombo 2) Floating market in Pettah 3) Pinnawala Elephant Orphanage 4) Adams peak - UNESCO World Heritage Site. Best views from the top 5) Yala National Park - to watch leopards 6)Mirissa Beach 7) Train ride from Kandy to Ella - the most beautiful train journey 8)Sunset at Dalawella beach 9) Sigiriya Rock Fortress 10) One day trip to Galle Happy travelling!!!!!
There are a lot of interesting things to do in Sri Lanka but given your tight schedule, you could explore some unique tourist attractions such as 1. Udawalwe National Park (it is one of the best spots in the world for elephant spotting) 2. A guided tour of Galle Fort 3. Trek to Sigiriya Rock Fortress 4. A visit to the architectural wonder, Anuradhapura 5. Taking a boat ride down the Kamuela River Good Luck!!
Happy Travelling!!