There is no short answer on how to get *easiest* from Dambulla to Sigiriya. Basically, you have to choose between the dirt cheap way (bus) and the comfortable and even scenic way (tuk-tuk).
Dambulla to Sigiriya cheap option: bus
The bus costs ~40 rupees one way per person. It leaves at the Dambulla Main Bus Station about 300m south of the clock tower on Kandy Road, which only serves short distance buses. The first bus departs at ~6.45am (yepp, there is no bus at 6.30am anymore, at least that’s the latest feedback I got from guests who tried it). The bus ride takes about an hour. Which means it takes 3 minutes to the second bus stop 200m north of the clock tower, where the bus waits for 10-15 minutes before proceeding to Sigiriya for the next 45 minutes. From the bus stop in Sigiriya it’s an easy 10 minutes walk to the ticket counter.
So with the earliest bus you can only make it to 8-8.15am at the Sigiriya ticket counter. After the first bus at 6.45am there is no fix timetable. You would just go to the bus station and wait for the next bus to leave, which happens approximately every 45-60 minutes. It also depends on the day of the week. On weekdays buses go more often than on weekends.
Going by bus can therefore be quite time-consuming. From your accommodation in Dambulla until reaching the Sigiriya ticket counter takes a while. In best case a bit more than an hour. In worst case (long walking distance to the bus station, just missed a bus) up to 2.5 hours. The last bus back to Dambulla is 6pm on weekdays, 5.30 pm on Saturdays and 5pm on Sundays. So no sunset viewing possible either. But still: It’s dirt cheap!
Fast and convenient option: tuk-tuk
The way more comfortable and faster option to get from Dambulla to Sigiriya would be by tuk-tuk (check here for good and reliable drivers). They are available at whatever time you prefer. You can choose between two routes. One option is the main road, which is really unexciting, but quick. In less than 30 minutes you will reach the Sigiriya ticket counter from your accommodation in Dambulla. If you leave at your guesthouse at 6.30am you’ll be just in time for the Sigiriya ticket counter to open. The usual charge for that route is Rs. 1500 (some tuk-tuk drivers try Rs. 2000).
The other and also the preferred route by our guests is the scenic road along the Kandalama Lake. It leads through paddy fields and farmer areas around Dambulla. It looks so beautiful just after sunrise in the morning! Some guests even declared this route the highlight of their Sigiriya tour. It takes longer, about 45 minutes, but it’s well worth the extra 15 minutes. The usual charge for the scenic road is Rs. 2000 and you should leave at 6.15am in order to be at Sigiriya before the masses and heat kicks in. If you need a good, reliable tuk-tuk driver, have a look here.
For more useful information and bits of advice on your Sigiriya visit, please check out my other post.
In addition to Sigiriya, I also recommend visiting the rock next to Sigiriya, called Pidurangala. A very good and detailed comparison between the two of them you will find here.