The Cross Island Highway runs 23 km south from Apia to Siumu. To the right near the road, three km south of the Lake Lanoto'o turnoff (and 13.5 km from Apia), are Papapapai-tai Falls, also known as Tiavi Falls. The viewpoint (free) is near a store beside the road but it's only worth stopping if you have your own transportation.
From Siumu the South Coast Road continues west, reaching Sinalei Reef Resort and Coconuts Beach Club after one or two km, Salamumu Beach after 11 km, and Return to Paradise Beach after 13 km. Catching a bus along this way would be pure chance.
One interesting south coast attraction is the Sa'anapu-Sataoa Mangrove Forest, accessible from either Sa'anapu or Sataoa villages. Each village has an information fale where you can pay an admission charge to visit the mangroves on foot (only at low tide), or a fee for an outrigger canoe tour (best at high tide).
You'll see two types of mangroves here, the red mangrove with stilt roots and the oriental mangrove with buttress roots of knee-like extensions. Birds include the grey duck and reef heron. The locals practice aquaculture and crab harvesting. Both villages have guest fale where you can spend the night.
The paved Lefaga/Safata road follows an inland course a few km from the coast and you must pay fees to visit the beaches. Return to Paradise Beach, named for a 1953 Gary Cooper film based on a James Michener novel of the same name, is accessible via a rocky two-km side road (admission fee). It's a popular picnic spot on Saturdays but visits are discouraged on Sundays.