Streets Beach
Brisbane is one of the only Australian cities that's not right on the coast. But not wanting to be without a beach, they made one. You can swim in the water or lie in the sand not far from the city center. The far side has a paved walkway where you can sit and dangle your feet in the water. There's a big river on the other side which I assume is the water source for this "lake".

This is the first sign I've seen which in addition to banning diving also specifically forbids cannonballs. (2nd row left)
This is the first sign I've seen which in addition to banning diving also specifically forbids cannonballs. (2nd row left)