How far away is kowloon, Hong kong from Ocean Park?

A little more than half an hour (or as much as 50 minutes) by bus (route 171/671/107/973 depending on where in Kowloon you are, get off after coming out of the Aberdeen tunnel and follow the signs)- save yourself the money. It's only HK$11.10 (except the 973 which is HK$13.60, thanks for the correction, Kingston D) by bus whereas you'll be paying more than 7x as much by taxi (as one HKer told me- each click the meter makes is another tug at your heart-and-purse-strings, so save your money and take public transportation).

The easiest way is to take the ferry over to Central or WanChai and then board the shuttle buses that will take you directly to Ocean Park.

A little less than an hour, if you go there by bus. If you go by taxi, probably around half and hour

The ocean park is on the southern tip of Hong Kong Island. If you take taxi, it takes around 20-30 minutes. It is very near as there is a highway that connects the exit of harbour tunnel and the district where the ocean park is at. If you are just 1-2 people, you can take MTR to the central station and then change to bus. It takes around 45 minutes but it is cheaper.

Yes, what Jamar says its right and you can actually head directly to the main entrance for those bus only if you are heading there on Sundays and Hong Kong's public holidays. For other days, what Jamar says 100% true and correct and not doubt about. Its largely depends on what route u take and the traffic condition along the way. 973 is HK$13.6 and not HK$11.10 stated by Jamar and its around 35-45 min for 973 from Salisbury Rd via Western Tunnel and others is correct for HK$11.1. 107 & 171 is a 30-40 min ride from Hung Hom Harbor Crossing near the Hung Hom MTR Station and 671 is 40-50 min ride from Diamond Hill MTR Station via Eastern Harbor Crossing.

If you take taxi, I think 20min is enough