Merri Creek runs northeast of Melbourne's CBD. It has a beautiful trail that follows its path. You'll be able bike, walk or run along it. This is a great opportunity to take a picnic as well, there are many spots ideal for it. Luckily, you can decide from which train station to jump off and start your trip and you can also choose if you want to take the train back in any of the nearby stations. I decided to bike all the way from the city to CERES, an environmental center, and go all the way back again. It was an incredible and enjoyable experience, it didn't take much time. Make sure you head out here if you want to do some exercise and enjoy nature. Merri Creek is also pet friendly.