The city is a popular summer destination because of its beautiful beaches - although the water can be very cold and the wind impressive.
The current population is estimated between 60,000 to 70,000 and the city has been growing rapidly in the last few years due mainly to the expanding tourism industry, fishing and Aluar-the aluminum refinery.
The government of Puerto Madryn has an official site about tourism in Puerto Madryn: 
Plane: Puerto Madryns Airport is located 10 minutes from downtown. Currently there are three flights per week from Buenos Aires on Andes Airlines. Aerolineas Argentinas flies to Trelew, which is an hour from Puerto Madryn. Shuttle buses operate from the airport in Trelew to Puerto Madryn and cost arg$20.
Puerto Madryn has a city bus system. Taxis are numerous. Rental cars are available.
To see the wildlife, it is cheaper to rent a car with other people than taking a tour. A car costs around 550 pesos (March 2013) per day with 400 km included (it's pricey for extra km). Gas will cost around 30 pesos per 100 km. Before setting off, you can ask at the tourist information centre in town or the one in Peninsula Valdes where are the best spots to see wildlife that day. The rangers go around the various locations early in the morning and tell the information centres which animals are where.
From Puerto Madryn daytrips run to Punta Tombo. This is a penguin colony where you can walk among thousands of penguins between the months of October and March.
Often combined with a visit to Punta Tombo is a boat trip to spot the small black-and-white Commerson's dolphins. Jun-Mar.
Many tour agents run trips to visit Peninsula Valdes. Here one can see penguins and a great number of sea lions and elephant seals, depending on the season. In January, all three can be seen (though no whales), including sea lions giving birth. Puerto Piramides is the only major town of Peninsula Valdes. Many tours will have a stopover here -- there is a nice beach and some bars and restaurants. There are boat tours and kitesurfers, among other things.
Punta Loma, 17 km southwest of Puerto Madryn is a sea lion reserve. It can be reached by bike. Beware- the road is not paved and your bike may sink into the sand. On the up side, there are deserted rocky beaches (very lovely) if you take any of the side paths off of this sandy road.
The EcoCentro is a great and modern marine interpretation centre offering interactive information on marine life in the region. Located overlooking the gulf to the south of the city on Julio Verne 784. Admission 95 pesos. 
Whale Watching, the Southern Right Whale uses the waters of Gulfo Nuevo for breeding and giving birth. They are easily seen from the shore and pier. Whale watching boats depart from Puerto Pyramides located on Peninsula Valdes.
Kite boarding and wind surfing.
Diving in Gulfo Nuevo. The water has very good clarity and no current.
La Tosca Hostel, Sarmiento 437, ☎ +54- 280-438-7277 (email@example.com), . Family run hostel with a couple of double rooms and a mixed dorm.
La Posada Hotel, Abraham Mathews 2951, ☎ +54280-4453525 (firstname.lastname@example.org), . La Posada Hotel has rooms with private bathroom, park, parking, swimming pool and more services.
El Gualicho, Marcos A Zar 480, +54 2965 454163 . Very popular and comfortable backpackers hostel. Offers very nice rooms and excellent travel information. More like a Hotel than a Hostel. Not very cosy/familial.
Posada Del Catalejo, Mitre 446, +54 2965 475224 . Excellent family run hostel. Friendly English speaking staff.
Viajero], Gobernador Maiz 545, +54 2965 456457 . Good location and very friendly staff.
Hostel El Retorno, Mitre 798, ☎ (02965) 456044, . Comfortable friendly hostel with a some private rooms and many beds in dorms. They offer pick-up at the bus station. You can call ahead to reserve.