However - and this is important - while the MICAT ferry drops you off there and there are places to hire kayaks, snorkels and wetsuits, there is not much else there. So if you go, you have to bring your own water, food and fun. Yes, you can get food and drinks on the ferry, but some people have been caught out when they go across not realising that there is nothing at The Wrecks itself.
The MICAT ferry leaves from the Port of Brisbane, and there is no public transportation to the ferry terminal. I have read that you can walk from the train station to the terminal and some budget travellers do this, but looking at the roads, I am not sure how doable this is. Instead, if you want to save money, you can take the train to Wynnum North Train Station and then take a taxi or ride share to the terminal.