how to get to ocean park from citygate novotel hotel in Lantau island? i have family of 7.

U can ask your hotel to arrange a transfer service for your family and I believe their charge can be reasonable. If you prefer public transportation, I suggest you take the free shuttle of the hotel to HKIA first. Then take Airport Express to HK Station. After getting off, walk to Central Pier no. 7 to take bus no. 629 to the park directly.