The responsiveness of benthic biological communities to climatic drivers and shifts makes them powerful indicators of biogeochemical and other environmental change in the oceans. In addition, benthic ecosystems have an economic value and are considered a vital marine resource. However deep-sea faunal dynamics and ecosystem functioning is not well defined. This has placed a higher priority in recent years on developing and sustaining long-term, time-series studies of benthic biodiversity, rate processes, and ecosystem change in deep-sea and extreme habitats. A few key long-term time-series sites exist across the global Ocean. Many of these sites are reviewed in this paper. However, much of the existing research is uncoordinated and the data collected are not integrated or standardized. This currently limits the use of these valuable datasets, which could be used for benthic modeling, global model validation and other societal benefits related to more effective and environmentally sustainable governance of human activities in the deep ocean. Furthermore, the time scales that can be studied within existing research frameworks are not currently sufficient to adequately address internationally-identified science priorities. These include assessing regional and global biodiversity, ecosystem functioning and the links between climate, terrestrial and marine ecosystems. In addition, the contribution of deep-sea ecosystems to global biogeochemical cycles and the potential alteration to ecosystem value and services due to anthropogenic activities is largely unknown. In order to maximize the societal benefit, biological time-series, in particular deep-sea sites, urgently require more coordination, integration, sustained funding and infrastructure. This is necessary to unify research methodologies, create synergies in the use of deep-sea technology, develop benthic models, and to stimulate more collaboration between programmes. National and international research organizations may provide a suitable framework within which further advances can be achieved. Only then will we better understand the goods and services provided by deep-sea ecosystems and the potential for environmentally sustainable exploitation of the deep ocean.