Penguins are awfully quick in the water. They may look awkward as they toddle about on land, but underwater they flash by you, slightly bobbing as they go.

Swimming with a penguin was pretty much at the top of my list when I went to the Galapagos Islands. After all, outside of venturing to the southern end of South America, when else would I get the chance?

Like much of the Galapagos wildlife, the penguins here are an anomaly, the only population of the flightless aquatic birds north of the equator. Along with blue-footed boobies, marine iguanas, giant tortoises, albatrosses and a host of unique finches, it's one of the animals people venture west of the Ecuadorian coast to see.

And like many of these animals, the penguins seem pretty much unperturbed by the presence of humans. The one I saw didn't swim close enough to be touched, but it did whip by just beyond arm's reach. Similarly, on visits to other islands, boobies and frigatebirds sat comfortably in their nesting areas while we snapped photos a few feet away. Iguanas lounged like they owned the place. And sea lions draped themselves on seaside beaches and rested on walkways like stray dogs.

Finding wildlife is not a problem.

But each of the archipelago's many islands – 13 to 18 major islands, depending upon how you define major, a handful of smaller islands and just over 100 rocks and islets – has its own unique environs, attracting its own combination of the area's animals and, often, a collection of flora not found anywhere else.

The biggest decision to make when planning a trip is what islands offer the combinations you want to see and whether to take a cruise. Most cruise boats are smaller, with space from 16 to 20 passengers, with larger ones accommodating as many as 100.Cruising is one of the most popular strategies for visitors, but you can also stay on four of the islands, either enjoying the sights there or venturing out on day trips to nearby islands. There are advantages to both.

Most cruises offer the all-inclusive, pre-planned experience that allows you to sit back and let someone else worry about the logistics. There are also a number of places cruise boats can access that are unavailable to day-tour operators.

Going land-based can be a lot easier on your wallet. Most day trips to other islands run $US150 to $US200 ($A162.29-$A216.39) per person (dive tours are more). Setting these up is rather simple. In Santa Cruz Island's Puerto Ayora, the largest town in the Galapagos, there are dozens of tour agencies competing for your business.

Hotel prices are surprisingly reasonable. In Puerto Ayora, we stayed in a three-person bungalow at a quaint establishment with a large pool, comfortable lounging areas and an impressive breakfast (included) for $US100 per night. Our accommodations on Isabela Island were more rustic but comfortable, and cost just $US49 per night.

The walkable downtown area of Puerto Ayora is a small strip of hotels, restaurants, tour companies and gift shops. One of its best features can be found after dark, when the kiosks (small open cafes) along Bordados El Alquimista fill the street with tables and chairs, creating a festive open-air restaurant where the fresh catches of the day are the featured fare. The local style is to cook the fish well done.

But most people don't come here to eat the fish. They come to swim with them, as well as the sea turtles, giant rays and the rest of the rich aquatic life the islands have to offer. And the best way to do that is to book a tour.

The entire Galapagos archipelago is a national park. Every tour, whether it's an eight-day cruise or a half-day hike, is required to be led by one of the park's 500 guides.

Maria Belen Egas is the head of volunteer programs for Galapagos National Park, headquartered in Puerto Ayora. She said guides have to take two months of courses through university extension programs in such subjects as science, environmental studies and English. To keep current, she said, guides have to periodically update their certificates with two months of refresher courses.

A recent law added one additional requirement: "Guides have to be from the Galapagos," Egas said.

She said the national park, which is celebrating its 55th year, works with the adjacent Darwin Research Centre, local institutions and NGOs to identify threats to the indigenous plants and animals, work on restoration projects and educate the public, especially residents.

IF YOU GO:

GETTING THERE: It's easiest to travel to Ecuador's capital Quito. Three Ecuadorian airlines – LAN, TAME and Aerogal – service Baltra/Santa Cruz and San Cristobal islands. All flights out of Quito stop in Guayaquil on the way.

PLAYING THERE: Be prepared to pay a $US100 ($A108.20) national park entrance fee, in cash, upon your arrival. There is also a $US10 transit control card that is required. Don't lose it; you'll need to turn this back in when you leave.Baltra is the most used entry port. A free bus takes you to a ferry ($US1) that bridges the narrow channel between Baltra and Santa Cruz islands. From there, it's a 45-minute ride by bus or taxi to Puerto Ayora.