Bay of Islands is in the northern part of the north island of New Zealand. A very known traveler destination, there are about 144 islands in the archipelago to visit and you can do all kinds of interesting activities, most of which involve the sea.
Bay of Islands hostels are located throughout the area in multiple cities, the most known of which are Paihia (widely considered the most beautiful place in the whole Bay of Islands area), Russell (a former shore leave place for sailors, which earned it the name "Hellhole of the Pacific"), Waitangi (a very historical town), Kerikeri, Opua, and Kawakawa.
Although the most conventional way of getting around NZ is with a car (either your own or a rental), Bay of Islands is also easily accessible with buses. There is also an airport in Kerikeri. There are plenty of Bay of Islands hostels, and like in many other places in NZ, the quality is really nice and the prices reasonable. The hostels will also help you arrange your activities and give you valuable information on what to do around Bay of Islands.
You won't run out of activities while staying at a Bay of Islands hosetl very easily. There are all kinds of cruises, snorkeling, diving and extreme sports to try out. Many towns have a lot of historical importance, like the famous Treaty Grounds in Waitangi. It is highly recommended to try out at least one cruise during your stay at a Bay of Islands hostel, because the Bay area is absolutely beautiful and the cruises are really good value, offering all kinds of activities. The cruises also give you the opportunity to meet other travelers and make some new friends.