Theme parks
Hong Kong has two major theme parks, both reachable by MTR, and pitched at fairly different audiences.
Hong Kong Disneyland
The smaller of Disney's parks worldwide, which in practice means shorter queues and an easier one-day visit than its US or Japanese counterparts. Strongest for younger children and Disney completists.
Ocean Park
A hybrid theme park and aquarium built into a hillside on the Island's south side, with a cable car connecting its two halves and a stronger lean toward thrill rides and marine life exhibits than Disneyland.
Which to choose
Travelling with young children and want a classic experience: Disneyland. Travelling with older kids or want more rides and animal exhibits in one visit: Ocean Park. Both are easily a full day.