Hiking in the morning always seems impractical for me. So I like looking for short trails which are accessible from MTR stations.
Near Quarry Bay Station, the Quarry Bay Tree Walk is around 1.1km in length. Signs are planted along the trail with introduction of trees like Polyspora axillaris (Big Head Tea) and Ormosia semicastrata. It overlaps with part of Wilson Trail Section 2 and Eastern Nature Trail, intersecting Mount Parker Road and Kornhill.
Area around the Quarry Bay Tree Walk is an important military base during World War II, where you can find abandoned stoves and warehouses.