The International code of safety (safety code) for ships operating in polar waters lists things like the design of ships, the equipment needed and the training operators need to travel in these dangerous waters. It also lists standards to maintain protection of the environments and avoid pollution.

Most likely a set of safety rules, some security protocol. Like every country has a road code - a set of rules according to which people drive or interact on roads.

Naomi's answer has the correct emphasis. Such a code is not only to protect the visitors, but also to protect the environment through specifying minimum capabilities and training.