Puerto Baquerizo Moreno
There are daily boats from Puerto Ayora in Santa Cruz. The two hour boatride is rough and noisy and costs approximately $25 one-way. Boats to Santa Cruz leave in the morning and boats returning to San Cristobal leave in the afternoon.
The island is small enough that unless you want to go to Puerto Chino, El Junco or La Galapaguera for the day or don't feel like hiking to El Progreso, you can walk wherever you need to be. From one end to the other Puerto Baquerizo Moreno is about a 20-30 minute walk.
If you don't feel like walking, hail a taxi (hold your hand out, palm sideways and point your arm towards the ground). It should be $1 anywhere in town (including the airport). El Progreso, Puerto Chino, La Galapaguera, and El Junco cost more and official prices have been established by the local government, check the board on the Tourist Pier for information on costs to these places. Since official prices have been established, no additional tax are allowed and Ecuadorians and foreigners are charged the same.
From town you can walk to Playa Mann, the beautiful local beach, although it can be quite crowded on weekends with locals and the occasional sea lion. It's right across from the campus of GAIAS, the Galapagos Institute for the Arts and Sciences of Universidad San Francisco de Quito. Just up the road is the Interpretation Center, with some great displays on the environment and history of the Galapagos. From there you can walk to Punta Carola, another popular beach, or hike the trail up to Las Tijeretas (Frigatebird Hill), which has a gorgeous view of the island and overlooks the bay where Darwin first arrived in the Galapagos. The bay has excellent snorkeling, but be careful, it can be dangerous depending on the tide and waves.
There are several tour agents offering boat trips and snorkeling to Kicker rock, Isla Lobos or other visitor sites. You can rent equipment to hike, camp, bike, or snorkel at many of these places. It's also possible to do scuba diving. There are three scuba shops on the island; GalaKiwi, Chalo Tours, and Galapagos Expeditions. GalaKiwi is better for experienced divers, the guide tends to swim fast and not point out too many things. Chalo Tours speaks English, Spanish, Danish, and German. They have reasonable prices and all the guides are great. The main guide for Galapagos Expeditions is trained by Chalo Tour's main guide.
Renting a mountain bike is also possible and cost around $10 per day. Most bikes are not mountain but are sufficient for around town and on the roads up to El Progreso (the other town on the island).
A taxi (pick-up truck) can be rented to drive to Puerto Chino, one of the best beaches on the island. It will cost between $40-50, but you can always grab a crowd and split the price. This is a gorgeous beach with soft white sand and is the furthest point into the island that one can go without naturalist guide.
While you're in the highlands, you may want to stop by the Galapaguera to see the breeding center of the San Cristobal variety of tortoises, which is right near Puerto Chino. El Junco, the only large freshwater lake in the Galapagos, is also a popular site.
There are several excellent places to surf around the island as well. During off season there are frequently waves at Punta Carrola and Tonga Reef. As the season picks up, El Canyon and a few other places have "buenas olas". Check with the locals about where the waves are daily and to ask for directions. IF there are waves, someone is almost guaranteed to be going surfing and most will invite you to follow them!
As in most of Ecuador, you can pay by cash or by credit card in most major places, although cash is preferred at most small shops and transportation. There is a Banco de Pacifico with ATM. Depending on your banknet, it may or may not accept your bankcard. If not, walk in the bank and talk to David about a Visa advance. He's a nice guy and speaks English. There is also a CPN ATM in town which supposedly accepts all the major card types.
There are many souvenir shops on the Malecón (Av. Charles Darwin) and the surrounding side streets. Galapagos coffee is always a popular item with prices ranging from $6.50/lb for vacu-packed coffee to $15/lb if you want it in a cute tin or box. Several talented local artists have a gallery in the upstairs of Casa Blanca, also on the Malecón.
Remember, never buy handicrafts made with local natural resources, it is forbidden by the Galapagos law, it is a National Park!
There are several excellent restaurants in town, and many smaller places that serve a good setmeal of soup, rice and chicken, typically around $3.
There are three main bars on the island; Polo's Bar, Iguana Rock, and Voqui Bar. Generally people start at Polo's (directly up the street from Calypso) and then head to Iguana Rock to dance (up the street from Polo's, hang a left when you hit the market). When Iguana's closes, head to Voqui for some late night pool (located in the back room of Calypso) or the sole Discoteca of the island, above Calypo's.
Instead of a discoteca above Calypso, there are now two discotecas in Puerto Baquerizo Moreno: La Isla (the island) and Neptune. Both are located on the main road and will sometimes charge a $1-3 entrance fee on the occasional Saturday.
It is generally easier to find cheap accommodation in Puerto Baquerizo than in Puerto Ayora on Santa Cruz. A/C rooms not too far from the pier can be had for $15 (maybe less) as of March 2016.
Camping is permitted in three locations on San Cristobal - Puerto Grande and Manglecito beaches on the west coast are only reachable by boat and a guide is required to camp with you (!) - Puerto Chino is the only place on the island where camping is possible without a guide. Permits ($10 per person) need to be obtained from the Park HQ near Playa Mann at least 24hours in advance (it says 48hours online but a friendly park ranger can be persuaded to issue a permit at 24hours notice).
To see the rest of San Cristobal Island, a taxi (pick-up truck) can be hired. A "tour" taking in the highland sites as well as Puerto Chino beach should cost $40-50 per vehicle. There is a bus on Sundays to Puerto Chino.
There are daily ferries to Puerto Ayora on Santa Cruz, one early morning, one in the afternoon.
Daily flights to Guayaquil from the airport, which is a short walk from town (10-15minutes) or a $1 taxi.