Does 'It is not possible to walk up through the water as at Dunn's River, but steps have been erected at the side of the water to take you to a platform at the foot of the first cascade.' stand independently of the premise 'Just as at Dunn's River, you can wade up through the water to the platform.', neither following nor contradicting it?
It is not possible to walk up through the water as at Dunn's River, but steps have been erected at the side of the water to take you to a platform at the foot of the first cascade.###Just as at Dunn's River, you can wade up through the water to the platform.