Brighton Park, Brisbane
Brighton park is a public park right my the estuary that you cross to go to the Redcliffe peninsular. It is tidal, so has some mangroves here.
Its a fairly barren spot, but there are some shelters and tables and chairs, and as per normal in Brisbane Parks, there is a free electric BBQ for public use.
A good spot for a family meal while traveling, there is room to let the kid run round, and also dogs are permitted if in a lead.