An Alanya Manavgat waterfall day tour with hotel pickup starts at a river, not a cliff: the Manavgat Waterfall is a broad, low cascade on the Manavgat River, a short way north of Manavgat town, with calm surroundings to walk through.
TurB2C lists one tour that covers it, a 6-hour trip from Alanya that adds Side, its Roman ruins and its old town on the coast. Below is what you actually see, in the order the tour gives it.
The Manavgat River runs down from the Taurus Mountains and reaches the Mediterranean near Side. At the waterfall it spreads across a wide ledge and drops in a sheet, so the effect comes from width and the sound of moving water, not from height. The tour lists the falls together with their peaceful surroundings, which makes this a stop for walking slowly, taking photos and standing in the shade of the riverbank trees.
Side was a port town in ancient Pamphylia, and its ruins sit right inside the modern resort. On this tour a guide leads you through Side Ancient City, which includes the ancient theater, rows of standing columns and other Roman remains. The guide matters here, because without one the stones are just stones. With explanation you can tell the theater's seating from the street lines and see how the city fitted onto its headland.
The Temple of Apollo stands beside the sea, and the tour lists it as a photo stop. A few columns remain upright against open water, which is why it is the picture most people take home from Side. After the ruins you get free time in Side old town. Its shops and cafés are close together, so you can have a drink, browse or simply walk the lanes at your own pace.
The tour runs about 6 hours and includes hotel pickup and drop-off, the guided visit to Side Ancient City, the stop at Manavgat Waterfall, time for shopping in the old town, and meals. Free cancellation is listed. Bring a hat, sunscreen and comfortable shoes, since ruins mean uneven stone. Spring and autumn are the easier seasons for walking. In midsummer the heat is strong, so carry water.