To reach there, you can take the KCR feeder bus "K52" (West Rail Tuen Mun station - Lung Kwu Tan) and get off at the terminus. Cross the road and you should see a large private barbecue site. Walk along the sea-side path behind the site for about 5 minutes and you should see a sign "Lung Kwu Tan Chinese White Dolphin Lookout". Walk up the stairs until you reach the bower.
From the bower, if you're lucky enough, you can observe the "Chinese White Dolphin". Remember to bring a pair of binoculars!
To reach the cache, walk for 5 more minutes along the path starting from the northern direction of the bower.
Besides Chinese White Dolphin, Lung Kwu Tan Village is also a great site for spotting butterfly. For more information, please visit Hong Kong Butterfly Net.