boat china gorges holiday life preserver life vest Ma Du Madu mini mountain orange protection river safety sightseeing tourism tourist travel vacation water danger fluro-vest height high lopping man man-at-work mechanical noise Noisy prune pruning saw tall tree trim trimmer trimming up-high workman attached attachments buoyancy buoyant canoe canoeing canoing cold connected equipment equipped estuary experienced gloved gloves kayaking kayaks lines motion movement moving outdoors paddlers paddles paddling prepared risks seated sit-ins sport sporting suitable suitably-clothed transport travelers travellers vests winter wintry