The Manly to Spit walk is quite a well known walk that follows the waterline from Manly (near Oceanworld) to The Spit (Spit Bridge). It's about 9km one way. It's a nice walk with enough variety in the scenery so you don't get bored.
Here's a few things I learnt from doing the Manly to Spit walk
1. Don't bring your bike. They ain't allowed on the path.
2. The first section out of Manly is like running through a park. There are dogs and people and kids all over the place. Persevere because the boring concrete path doesn't last forever.
3. Sunday mid-morning is peak hour on the path. If you have the option to do it on a weekday do it. on a weekday.
4. Keep an eye out for turn-offs. The signs are easy to miss at some points. If you end up in suburbia like I did then you've missed a turn off.
5. The path is a bit up and down, up and down. And, then it goes up. And up. And up. You find yourself wondering when the uphill ends. Don't worry, it does end. And, the view from the top is absolutely worth it.
6. Once you hit the top it's down hill for a while. This turns into the nicest part of the trail. It's rocky and uneven. The path is narrow and it even feels tropical in parts. This is the part of the trail that makes you feel like you've really escaped the city.
7. Pick a day that is sunny. Actually, pick a day that is sunny and has had several sunny days preceding it. Otherwise, the path can get really muddy and slippery in parts.
8. When you get to the beach at Clontarf if it's really windy (like it was on the day I went) look for the street detour on the right.
9. When you finally make it back to Manly make sure you don't stop walking till you get to Zumbo ; )