Head North up the Pt Wakefield Rd, the Main North Rd leads onto this from town. Turn left at the turn off to St Kilda. It's a fairly straight road to the coast.

Keep an eye out for the best ever DIY extension on your right( a shed held onto the top of a house by some ropes and poles).

St Kilda Tramway museum. Open 1-5 Sundays and also Weds on school hols. Adults $10, Family $28, Concession $7, kids under 4 are free.
Before you get to the end there is the Tramway museum.It's on the left, a couple of ks along. This has a collection of historic trams that will run you up and down the the tramway to the St Kilda playground. You can ride as many trips as you like for the admission price and can get off at the playground too.
There are also static trams that you can get on and see the history and the demise of the tramways in Adelaide.

St Kilda playground Fooks Tce, St Kilda entry free.
Has adventure type play equipment, slides, flying foxes( not animals those tarzan swings on a cable), tunnels, a ship etc. there is an area for picnics and bbqs and toilets.

St Kilda Mangrove walk. Entry off Fooks Tce near the Marina. Adults $6.90, Child u17 $3.90. Open 10-5
This is about a 2k walk through the mangroves on a wooden pathway, through the tidal estuary. You can spot birds and plants and just the mangroves themselves are interesting. There is also a visitor centre with loads of info. Sometimes the mangrovescan stink a bit, but it's something different to do.