From Diving Sites Toward Sustainable Underwater Trails: Formal and Informal Routes, Underwater Attractions, and Nature Conservation Considerations in Selected Polish Case Studies

Inland diving sites may contain routes, attractions, and infrastructure, but these elements do not determine how a future underwater tourist trail should be organized. This study applies an emerging pre-implementation framework using an 85-record database of Polish inland diving sites compiled from specialist diving sources, operator and institutional materials, maps, and scientific publications. All records were screened; thirty-seven identifiable arrangements in 31 records were assessed using three route-confirmation criteria (T1–T3): spatial identification, reproducibility, and current use. Confirmed arrangements were characterized by organizational status and a seven-feature formalization profile (F1–F7). Seven local cases and one auxiliary spatial-scale case were then selected to examine resource relationships, alternative trail-organization variants, and seven pre-implementation assessment areas (Z1–Z7). Twenty arrangements in 17 records were confirmed: 16 formal, two informal, and two with undetermined status. Guidance and current documentation were more often confirmed than ongoing maintenance. Case analysis showed that resources may be retained, separated, connected, or used selectively, but no single configuration suited all cases. In all seven local variants, relationships with sensitive environmental features remained undetermined; user information was incomplete and long-term maintenance was not fully confirmed. The framework structures decisions and identifies evidence gaps before design; it does not certify achieved sustainability.