You can stroll along Kowloon Bay 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 Kai Tak Cruise Terminal and Kowloon City Ferry Pier for some more water views.
If you like quiet time surrounded by flowers and greenery, hang out at Kowloon Walled City Park in Kowloon City. Why not take a stroll along the port and watch the sunset while you're here? It's also full of great shops and restaurants, so you can spend the afternoon having a wander. Want to stretch your legs some more? Head to Hung Hom Promenade and Kowloon Park, both nearby.