Info from Hong Kong's Great Outdoors
A network of paths links the villages and hamlets of north Lamma. One option for a half-day or day visit is to take a ferry to Sok Kwu Wan, then walk to the other ferry pier at Yung Shue Wan (or vice-versa). Southern Lamma is far wilder than the north, dominated by hills including 353-metre Mount Stenhouse. A trail that meanders above the tideline south of Mo Tat, then crosses a ridge northwards, makes for an away-from-it-all hike.
Ferry from Outlying Islands pier, Central, to Sok Kwu Wan or Yung Shue Wan; or ferry from Aberdeen to Sok Kwu Wan.
Lamma article on this site
Lamma Island: Yung Shue O to Sok Kwu Wan is a short article on walking between the two villages (each of which has a ferry pier).