Wreck Diving Glossary

Difficulty is assigned per wreck from depth, access, current, surge, navigation difficulty and overhead environment together. It is this project’s own rating, not an agency standard, and it exists so that two wrecks at the same depth are not presented as equivalent dives when they are not.

Beginner

Shallow, generally sheltered, no overhead environment, reachable by a newly certified diver. Depth alone does not earn this rating — an exposed shallow site subject to surge is rated higher.

Intermediate

Typically within 30 metres, suiting a diver with an Advanced Open Water certification or equivalent and some post-certification experience.

Advanced

Deeper, or complicated by current, navigation difficulty or partial overhead. Assumes wreck diving experience rather than simply a card.

Technical

Beyond recreational limits. Requires decompression procedures and, in most cases, mixed gas.

Extreme

Deep trimix territory with long run times, significant logistics and little margin. Reserved for sites where an equipment or planning failure is not recoverable by ascending.

Certification is deliberately split across several fields. Agency names that appear in records — Open Water, Advanced Open Water, BSAC Sports Diver, trimix and so on — carry the meaning their issuing agency gives them.

Minimum certification

The lowest qualification at which the dive is legally permitted or at which operators will take a diver. A hard floor, not a recommendation.

Recommended qualification

The level at which the dive is reasonable rather than merely permitted. Usually above the minimum.

Recommended experience

Logged dives and the kind of diving they should have been. Held separately from certification because the two are not interchangeable.

Penetration possible

Whether the structure physically admits entry. It is a description of the wreck, never an endorsement.

Overhead environment

Any part of the dive where a direct ascent to the surface is blocked. Overhead diving requires specific training regardless of depth.

Access method

How the site is reached — shore, boat or liveaboard. Shore access does not imply an easy dive.

Nearest port

The harbour dives normally run from, which sets transfer time. Several offshore sites involve three hours or more each way.

Intact

Hull substantially whole and recognisable as a ship.

Broken

Hull failed into sections, often still with identifiable structures such as boilers, guns or machinery.

Scattered

Debris field rather than a wreck. Frequently the outcome for shallow sites on exposed coastline.

Orientation

How the wreck sits — upright, listing, on her side, or inverted. Inverted wrecks are disorienting and change how the dive is planned.

Typical visibility

The range published sources most often report. It is a pattern, not a forecast for a given day.

These are legal terms, not descriptive ones. Their force comes from the relevant national legislation, and their application to a given wreck is recorded with the source and date it was checked.

War grave

A wreck designated as the resting place of those lost with it. Artefact removal is prohibited; at some sites diving itself requires permission or is banned outright.

Protected status

A legal designation — such as a scheduled monument or national monument — that restricts what may be done at the site.

Permit required

A licence or permission must be obtained before diving. Who issues it varies by jurisdiction and is recorded per wreck.

Artefact restrictions

Rules on removing material from the site. In most covered jurisdictions removal is an offence on protected wrecks.

How these are sourced and rated is set out in the methodology, and what the database does and does not cover is on the coverage page.