Shorncliffe Foreshore has just had renovations done. There's a great park near the Jetty and rock pools to play in along the shore.
Things to Do:
Look at the boats in the Marina, play in the park, look for sealife in the rockpools.
Take a Shorncliffe train from Northgate.
Sunscreen and a Hat
The View from the top of the cliffs
Other Options: Keep walking along the foreshore to Sandgate where you can visit the lagoons.