Diving deeper: a systematic review of sustainable scuba diving supply chain

Introduction Scuba diving tourism depends on a chain of actors (certification agencies, equipment suppliers, dive operators, intermediaries and divers) that draws on a shared natural asset, the dive site, yet it has rarely been examined from a supply chain perspective. Methods This systematic review, reported according to PRISMA 2020, synthesizes 188 studies published between 2004 and 2026, identified through searches of Scopus, Web of Science and Google Scholar, citation chaining and a fully documented search of OpenAlex, and selected with a strict supply-chain eligibility rule. Each study was coded for its supply chain tier, design, evidence type and the framework relationships its findings bear on. Results Only 25 studies (13%) analyse scuba diving tourism as a multi-actor chain or system; 148 examine a single actor or process, and 15 adjacent tourism supply chain studies are used for theory transfer. Evidence is concentrated on dive operations, divers and the natural capital foundation, while equipment supply is almost unstudied (eight studies). Observational and stated-preference studies consistently link better reef condition with higher diver demand, prices and willingness to pay, and observational studies associate operator environmental certification with lower reef contact, while the evidence on training standards, supervision and briefings is mixed; stated-preference and modeling studies indicate that moderate user fees can finance management with little loss of demand. Evaluated interventions are rare, the one evaluated quota lost its effect within a few years, and claims about collaboration, leakage, equipment supply and strategic interaction among operators rest on limited, descriptive or adjacent evidence or remain untested. Discussion The review proposes the Sustainable Scuba Diving Tourism Supply Chain (SSDTSC) framework, a five-layer model in which every relationship carries an explicit evidence status, and sets out a research agenda that prioritizes intervention studies, chain-level data on value distribution and the governance of shared dive sites.