You can stroll along Kai Tak Cruise Terminal for relaxing water views when you're in Kowloon City. It's also full of great shops and restaurants, so you can spend the afternoon having a wander. If you carry on walking you'll get to Kowloon Bay for some more water views.
If you're planning a bit of sightseeing head to Kwun Tong Promenade— just one of the monuments in Kwun Tong.