澳洲柏斯潛水

the closest place should be rottest island, its close to Fremantel.....you can catch a train to fremantel, then walk to the jetty ( about 10 mins walk)

its about $ 50 for return ( 2 years ago....)...then when you arrive at rottest island, there is a dive shop, you can join the day trip there ....

http://www.rottnestdiving.com.au/

about 1.5 hours drive south to perth is also a great place to snorkel and dive...its call Rockingham

however both place that are close to perth is not the greatest place for diving in WA , the best diving spot is in exmouth - which is the second biggest reef in australia - it is as beautiful as great barrier reef but far more easily to access the reef from beach