It depends especially on the level of comfort and facilities on board you are looking for:
First, you must get to Ecuador Mainland. Make sure you arrive to Quito or Guayaquil at least one day before your departure to the Galapagos; there are no direct connections with international flights and flights to Galapagos Islands depart from mainland Ecuador early in the morning from Quito and/or Guayaquil.
Visitors arrive by plane from Mainland (flight takes about 2 ½ hours) with three main Airlines: AVIANCA, LAN and TAME and arrive to Galapagos to one of its two Airports: One in Baltra Island and one in San Cristobal.
In general, cruises include: accommodation in cabin with private facilities, guided excursions with professional Licensed bilingual guide, transfers within Galapagos (on cruise dates), Airport assistance, all meals on board while cruising, drinking water, tea, coffee.
Luxury and First class cruises also include usage of snorkeling equipment and most of them have sea-kayaks on board for guests. Some Luxury class cruises also include Wet suits and others and First class cruises have them available for rent on board.
Midrange and Economy class cruises have snorkeling equipment and Wet suits available for rent on board (in cash).
On a general basis, unless included on the given price for the confirmed cruise, passenger needs to bring enough cash on board to cover costs like Galapagos entrance fee ($100 p.p. in cash on arrival to Islands), mandatory Transit Control Card ($20 p.p. paid before check-in in cash), snorkeling equipment & wet suit rental (in cash on board), personal expenses, extras, soft & alcoholic drinks, tips for guide& crew and other expenses not specified in the itinerary.
Some Luxury and First accept Credit Card payments on board for on board consumption but Midrange and Economy require payments in cash only. It is imperative that you bring enough cash (U.S. Dollars) in all cases to cover your expenses while cruising the Galapagos.
Although the Galapagos Islands are located in the Equator, but it has moderate, drier climate rather than typical tropical weather. This because of three confluent Ocean currents that determine the two yearly seasons in the Archipelago: cool/dry season from mid-June to early-December and the wet season from mid-December to early-June.
Average temperature range: 69°-84°F / 21°-30°C. Weather in Galapagos has variations on each season.