As damhooligan has mentioned, there's no new track between Altona and Sanctuary Lakes but I can add a little detail to what damhooligan has suggested.
I'm taking all the street, road names and directions off Google Maps for this description.
From the Town Centre shopping area, head south down Mail St. to Dunnings Rd.
Turn left onto the cycle lane at Dunnings Rd.
After about 500 mts, on the right you will see Lemmon Boulevard.
Turn right into Lemmon Bvd. No cycle lane at this point but the traffic is slow down the Bvd.
At the first roundabout, turn left and follow the road around the small park until you again meet Lemmon Bvd.and left to follow the Bvd.
Continue down and pass Jamieson Way until you pass over a small bridge over the creek.
Directly after the bridge at the small roundabout, you will see a path following the creek.
Turn left onto the path and follow it along. Although there are no signs, I believe it is a shared path.
Cross La Rouchelle Bvd and the track will bring you onto Jamieson Way at the Community Centre.
You will need to follow Jamieson Way for a short distance to Point Cook Road, it's pretty quiet here and there are a couple of roundabouts to keep the car speed down. There is more traffic as you reach the Sanctuary Lakes shopping centre but it's usually well behaved.
At the Point Cook Rd intersection, you have the choice of riding through the roundabout en masse, (safety in numbers?) or dismounting and using the pedestrian light controlled crossing on your left.
Continue directly ahead into Sanctuary Lakes Bvd.
As you reach the large roundabout, you have a choice.
You need to go through the roundabout heading directly for the lake path which is right in front of you at this point. You can see the layout of the path in the Google satellite view.
You can go to the left along the path which is a shared path or,
you can go to the right which is also a shared path.
If you go left, follow the path which is following Sanctuary Lakes Boulevard North until you see the water in front of you again at Sanctuary Lakes Bvd. East. If you cross the Bvd. towards the water at this point you will see the path turning to the left and following the lake side. As you come to the end of the path, it's only a short stretch, you will see in front of you, Beach Walk. Travel up Beach Walk and you will come to the bike path and bridge over Skeleton Creek.
Google Maps and Satellite are too old to show the detail so take a look at this link instead and you should be able to see the detail.http://www.nearmap.com/?ll=-37.898325,1 ... d=20120225
Just a couple of hundred metres after the bridge will bring you back to the Altona path.
If you go to the right, you will pass through the built up area until you reach the new sub division. There's a lot of work going on in this area building the new houses but it is fairly quiet on a Sunday. Saturdays are still fairly busy.
Here, you will be following Sanctuary Lakes South Bvd.
On the path, continue down and through the building area until you reach the point where the lake meets and drains under the road.
Directly after the bridge, on the right you will see where the bike path travels along directly behind the house and bordering on the Cheetham Wetlands.
This link showing the photo map from Nearmap will again show the bike path where it starts just after the bridge.http://www.nearmap.com/?ll=-37.90244,14 ... d=20120225
Follow the path until it brings you to the bridge over the creek.
As you can see, the South Bvd route is a little shorter but there can be a little traffic in the building area where you will have to ride on the road but only for about 500 mts. The road itself is quite good to ride but narrow in places, speeds are low and there isn't a lot of traffic.
The North Bvd is longer but bike path all the way but taking care where you cross the streets. The road is quite narrow for most of the distance but again, speeds and traffic are low. Single file is really the only way to travel on the roads in the area.
It's not a bad ride through the Sanctuary Lakes area but it does remind me of this old song,http://youtu.be/4poWiKfg1MU
For the best maps and photos, I suggest, https://www.nearmap.com/welcome-new
I hope you enjoy your ride.