This is a great 20 km hike, perfect for a sunny spring day. Make sure you pack your togs (aka: bathers, swim wear etc) as there are plenty of opportunities for a swim in the bay.
The hike starts at the end of the 109 tram line, Port Melbourne. If you need a morning pick-me-up, grab a coffee at one of the cafes - Rock Paper Scissors is close by and a goodie.
As you walk west along the Bay Trail, make sure to keep left as most of this hike is on shared paths - so keep alert for bikes!
When you get to Todd Road, follow it north for about 1500 m (it's not the quietest of walking), under the West Gate Bridge and into Westgate Park, one of Melbourne's well-kept secrets. Once an industrial wasteland, Westgate Park has been lovingly restored to a flourishing wetland and offers some great views back over the city. The park's lake sometimes turns pink due to natural seasonal variations in salt and temperature, causing the algae in the lake to produce a pinky-orange pigment called beta-carotene when the water gets very hot and salty.
As you hike through the park, look out for Lyn Moore's Earth Series sculptures.
Soon you will reach the Fishermen's Bend ferry service. The fare is $2.70 one way on weekdays and $5.00 each way on weekends, and you'll need cash to cross. Check out their website for crossing times https://www.ptv.vic.gov.au/getting-around/ferries/westgate-punt/.
On the other side, head south through Riverside Park. If you're in the mood for a midday brew, Two Birds Brewing is only a short detour. Or, if another coffee is needed, stop by at the Pint of Milk to refuel. Continue south along the Bay Trail West.
Williamstown is the next stop, and depending upon what time it is, will be the easiest place for a lunch stop. There are loads of places to choose from, including an array of fish and chip shops - try Off the Pier for a quick and easy takeaway. You can wander out to the pier and back and check out the HMAS Castlemaine if you have the time.
After lunch, head out of town south following Battery Road to Point Gellibrand Coastal Heritage Park. Here's where the hiking gets decidedly less urban and industrial, and a lot more scenic.
Continue to follow the Bay Trail West. Once you reach Jawbone Nature Conservation Reserve, keep an eye out for birds such as swans, herons and spoonbills.
Follow the trail around down Maddox Road and around the soccer club. The Kororoit Creek is initially blocked from view by some quirky and ramshackle boat houses.
The salty marshes are home to white mangroves, frogs (including the endangered Growling Grass Frog) and an array of snakes - so remember to keep a sharp eye out in spring and summer.
The trail crosses the creek at Racecourse Road, and there are two options from here; continue to the right along the Bay Trail, or head straight on out into the Altona Coastal Park. I recommend the second option as it takes you away from the road.
Rejoin the Bay Trail West, cross Cherry Creek and head south-west through WG Cresser Reserve until you pick up the Esplanade. Here we saw quite a few spoonbills close to the path, as well as Black-winged Stilts and Red-necked Avocets.
Altona Pier is your last stop, and if you still have the energy, its a nice walk out to the end on a warm day. The beach is usually fairly calm and a good place for a swim to cool off.
There are some reasonable places to eat in town if you arrive for a late lunch or early dinner. My pick is Harmony Vietnamese - they do a good Pho and Bun (vermicelli with pork and spring rolls) at a great price.
Return to Melbourne via the Altona Train Station - trains run fairly regularly and it takes about 45 minutes to get to Spencer Street Station. Or if you're keen for a night out on the coast, consider finding a Bed and Breakfast, and explore Truganina Park and Cheetham Wetlands the following day.