Seabird populations, important components of the marine ecosystem, are decreasing due to human activity impacting the oceans. In order to conserve seabirds, it is essential to conduct monitoring studies of seabirds and to understand how factors affect the dynamics of their populations and their breeding success. Here we introduce methods of seabird monitoring on beaches and oceans, including beached bird surveys and ferry censuses, and explain their fundamental significance for monitoring studies. In beached bird surveys, researchers record the carcasses of seabirds found while walking along a certain length of beach. Citizens interested in seabird conservation can easily conduct such surveys and contribute to continuous monitoring studies. During censuses from ferries, researchers count the seabirds resting on the sea surface or flying from the vessel and record their behavior. Research vessels, trading ships and ferries can all be used for such censuses. Censuses from ferries are feasible for amateur birdwatchers with binoculars. Seabird researchers aim to identify “Marine Important Bird Areas (Marine IBA)”, areas and habitat seabirds use frequently. Ferry censuses can provide important information to detect Marine IBA. Beached bird surveys conducted by amateur birdwatchers play an important role in providing information on the occurrence of oil spills and bycatch in Marine IBA. Beached bird surveys and ferry censuses conducted by amateur birdwatchers are expected to be extended and carried out at many sites continuously.