Regulations for the National Park
As befits its historical and environmental importance, the whole of the Galapagos Islands is controlled by the Galapagos National Park Authorities, who are charged with not just maintaining the islands as they are but - where possible - helping to restore the islands to their condition before they were damaged by introduced species and by humans themselves.
In order to ensure that the National Park is correctly funded, on arrival in the islands you will be required to pay the $100 National Park Entrance fee. This helps fund the maintenance of the parks and other national projects and is distributed as follows: 40% goes directly to the Galapagos National Park Authority; 20% to the Galapagos Municipalities (equivalent of councils); 10% to the Galapagos Provincial Government; 10% to the Galapagos National Institute (INGALA); 5% to the Galapagos Marine Reserve; 5% to the Galapagos Provincial Inspection and Quarantine System; 5% to the INEFAN (National Park Service); and 5% to the Ministry of Defence, who provide coastguard services. As you can see, the fee goes directly to organisations who study and protect the islands so consider it an investment!
Before boarding your flight from the mainland, you will also have to purchase the $10 INGALA Transit card, the proceeds of which go directly to the Galapagos National Institute. At the INGALA desk they will also screen your luggage for organisms foreign to the Galapagos, such as seeds and insects, as the introduction of non-native specis can do irreparable harm.
Common Sense Rules
Aside from this, the National Park Regulations are mainly common sense rules, regarding respect for the wildlife in the park (essentially: don't feed or pet the wildlife as it can alter their natural behaviour) and the park itself (eg: never drop rubbish, even if it's bio-degradable).