Southern Sydney is an arbitary district name, for the area south of Sydney and north of the Georges River, including Sydney Airport and Brighton le Sands area. It is primarily a residential and commercial area for Sydney. While many travellers only travel through this area on the way to and from Sydney Airport, it has some intereresting sights of its own.
By rail, the western extent of this region is served by CityRail's Eastern Suburbs and Illawarra line. The Airport and East Hills line has premium-priced stations  serving the airport and adjacent area.
By bus, from the city, Sydney Buses  routes 309 and 310 access the Mascot and Botany area. The daytime high-frequency Metrobus M20 (prepay only) connects Mascot to the city and over the harbour to the Lower North Shore. Brighton-Le-Sands area is served by the 303 bus from the city.
When driving via the Airport Tunnel, be aware that tidal flow lane control operates during morning peak hour. Be sure to look at the electronic overhead signs and lane markings and not blindly follow your GPS!
Captain Cook first landed in Botany Bay in 1770, and raved about the place. However, when the first fleet of convicts arrived 18 years later to start the colony, they didn't care it. Too sandy, and no fresh water, and they moved on to Sydney Harbour. Since then sections of Botany Bay have been reclaimed for container terminals and Sydney Airport, and industry and oil refineries built on its foreshores northern and southern foreshores. However, the bay is still popular for swimming and windsurfing, and a 10km walking cycleway runs along its foreshore from Kyeemagh to Dolls Point. There is a memorial to the first fleet. Cafes, restaurants, clubs, ice cream are available also. Parking is usually available, except on the busiest of summer weekends. Public transport access is by train to Rockdale, and then 478/479 bus to Brighton le Sands. Both services run frequently. 
Oatley Park - one of the finest examples of Australian remnant bushland about 30 minutes drive of the CBD. Features bushwalking, swimming, bike trails as well as play equipment for children. The lookouts over the Georges River are also well worth a look. There is plenty of parking in the park, or it is about 2km walk west of Oatley Cityrail  Station.
Cruises - Bass and Flinders  cruise the Georges River every Sunday. The wharf is just adjacent to Captain Cook Bridge in Sans Souci. Plenty of parking, or catch the bus heading towards Miranda from Rockdale.
Planespotting from the carpark behind the old control tower on the shore of Botany Bay adjacent to the main north-south runway. The carpark is closed after dark. There is a small beach and access to the security fence only metres from the main runway. At dawn you may see some of Sydney's racehorses being led into the water here for a swim. Car & pedestrian access is from General Holmes Drive, and there is an infrequent bus service.
Alexandria is the city's outlet centre, adjacent to Green Square station in Alexandria.
Sydney Luggage Centre, 1147 Botany Rd, Mascot, ☎ +61 2 9669 6381, . Mon-Fri 8:30AM to 5:00 PM (Sat to 3:30 PM, closed Sun). Made it all the way down under and that wheel has fallen off your suitcase? Come here to get the spare, or buy a sturdier replacement. This long-established luggage retailer is one of the largest in Sydney (CBD store also). Service over the phone can be limited. edit
Hong Ha, 1151 Botany Rd, Mascot, ☎ 9667 2069, . This tiny Vietnamese bakery is an institution. Visit the original store, which gets queues down the street at lunchtime, and order their famous chicken roll (with optional fresh chilli).edit
South Sydney Graphic Arts Club, 182 Coward St, Mascot (Between Botany Rd and O'Riordan Streets), ☎ +61 2 9667 4321, . Opens 10AM (Mon-Fri), 12PM (Sat-Sun), closes 10PM (midnight on Wed-Sat).. This is a members' club, but not if you live more than 5KM away, so take advantage of this little secret for cheap drinks & eats. Tuesday nights have even cheaper meals.edit
Quality Hotel CKS Sydney Airport, 35 Levey Street, Wolli Creek (From the International arrivals terminal, from Arrivals court veer onto Cooks River Avenue . This becomes Marsh Street. Take the first right into Innersdale Road and the first right onto Levey Street. The hotel entrance is on the left. From the Domestic arrivals terminal, first turn left onto Qantas Drive this becomes Airport Drive. Take the first right into Innersdale Road and the first right onto Levey Street. The hotel entrance is on the left.), ☎ +61 2 9556 1555, . checkin: 14:00; checkout: 10:00. Quality Hotel CKS Sydney Airport is located minutes from Sydney International & Domestic Airport. The Sydney Airport hotel features modern rooms, on site restaurant, bar, free Wi-Fi & more.edit
Hotel Formule 1 Sydney Airport, 5 Ross Smith Ave, Mascot, ☎ +61 (0) 2 83391840, . checkin: 12:00 PM. Closest hotel to the domestic terminals T2 and T3, this is a basic budget hotel with convenient access to 24 hr Krispy Kreme and McDonald's next door.edit
Stamford Plaza Sydney Airport Hotel, Cnr O'Riordan & Robey Streets, Mascot, ☎ +61 2 9317 2200, . A short walk north from the domestic terminals T2 & T3. This is a well-appointed 4* hotel. Tip: Ask for an upper-level airport view room, it's one of the best outside the control tower!edit
Holiday Inn Sydney Airport, Cnr O'Riordan St & Bourke Rd, Mascot, ☎ 1800 899 960, . checkin: 2:00 PM; checkout: 11:00 AM. A longer walk (10-15 min) from the domestic terminals, this hotel has the advantage of being very close to Mascot Cityrail station, providing quick and cheap access to Sydney CBD.edit
Mercure Sydney Airport, 20 Levey Street, Wolli Creek (walk west from the terminal over the bridge along Marsh Street), ☎ +61 2 9518 2000, . The only hotel within walking distance from the international terminal (T1). Formerly known as the Hilton. A taxi to the international terminal costs about $7-8, there is also a shuttle bus which costs $6.edit
Rydges Sydney Airport, International Terminal. Due to open by late-2012, this 4* hotel will be conveniently located adjacent to T1.edit
Novotel Brighton Beach, (opposite the beach at Brighton le Sands), ☎ +61 2 9556 5111, . By far the largest hotel in the district, linked to Brighton Beach by a footbridge. Situated in the heart of the restaurant area along Bay Street.edit
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