Since the Galapagos Islands are in tropical regions, you should dress in light, cool clothing and bring a sweater or jacket and pants for the cooler evening temperatures. Hiking or tennis shoes will be needed to explore the island’s rough terrain although for some land visits tevas or sandals will be fine. For the larger yachts you should bring another pair of footwear to keep dry and wear on the boat, but on smaller yachts there is a policy of barefoot on board usually. A sun hat and sunglasses are also recommended to protect you from the hot equatorial sun. Although some items can be bought in Puerto Ayora in the Galapagos, they can be pricey and not always available so you should plan to bring everything you will need with you, including extra supplies of such items as film and batteries. 

Bathing suit
Wind break and light pullover
Rain protector (optional)
Hiking shoes
Sandals or tevas (optional)
Normal shoes (larger ships)
Toiletries
Insect repellant
Suntan lotion
Binoculars
Flashlight/batteries
Camera/film/batteries (spare films can usually be found in Puerto Ayora)
Snorkeling equipment (if not provided on the boat)
Wet suit or lycra skin (optional but recommended July-Oct)
Passport
Cash/credit cards/traveler’s checks