The impacts of mass tourism and COVID-19 crisis demonstrate the need for healthy, peaceful, and authentic recreation options, giving prominence to emerging destinations, such as remote Mediterranean islands. These, although endowed with exquisite land and underwater cultural heritage (UCH), are confronted with insularity drawbacks. However, the exceptional land and especially UCH, and the alternative tourism forms these can sustain, e.g., diving tourism, are highly acknowledged. The focus of this paper is on the power of participation and participatory planning in pursuing UCH preservation and sustainable management as a means for heritage-led local development in remote insular regions. Towards this end, the linkages between participation and (U)CH management from a policy perspective—i.e., the global and European policy scenery—and a conceptual one—cultural heritage cycle vs. planning cycle—are firstly explored. These, coupled with the potential offered by ICT-enabled participation, establish a framework for respective participatory cultural planning studies. This framework is validated in Leros Island, Greece, based on previous research conducted in this distinguishable insular territory and WWII battlefield scenery. The policy and conceptual considerations of this work, enriched by Leros evidence-based results, set the ground for featuring new, qualitative and extrovert, human-centric and heritage-led, developmental trails in remote insular communities.