Methodology

How we summarise reviews

Some instructor and dive centre pages carry a short summary of what reviewers elsewhere on the web have said, and the directory orders listings partly by how much technical review evidence exists for them. This page sets out exactly how both are produced, including what we throw away and where the method is weak.

Where the reviews come from

Public reviews for each dive centre, chiefly Google Maps, fetched per centre and stored as written. We do not edit review text, and we do not solicit reviews. Where a centre's operator or a reader sends us reviews we have not fetched, those are added to the same store, marked as supplied rather than fetched, so that every number on the site can be traced back to a specific piece of text.

Reviews written on TecDiveTools itself are a separate thing entirely. They carry a star rating, they are shown under their own heading, and they are never mixed into a synthesis or into the counts described here.

What counts as a technical review

This is a technical diving directory, so a glowing review of a reef trip is not evidence about technical instruction. A review counts toward a listing when it passes all of these:

1. 1

   It names a technical or overhead subject

   Cave, cavern, rebreather and the units by name, trimix, decompression, sidemount, DPV, drysuit, twinset, stage cylinders, extended range, Intro to Tech, GUE Fundamentals, CCR MOD levels, and the agency names that only appear in technical contexts. Terms sitting on the line between technical and recreational, like a drysuit or a DPV, are included deliberately.
2. 2

   It is about training or guiding

   Both of these, not either. Praise with no subject — “an experienced and kind instructor” — does not count, and neither does a fun dive with a technical instructor. Guided diving counts when it is guided technical diving.
3. 3

   It is not an entry-level certification review

   Reviews about open water, advanced open water, rescue, discover scuba, try dives and refreshers are excluded. A review that mentions one of those and a technical subject still counts — “I did my open water here and came back for cave” is technical evidence.
4. 4

   It is about that person

   The instructor's name has to sit close to whatever qualified the review, not merely somewhere in the same paragraph. Without this rule the person who answers the phone gets credited with everyone else's teaching.
5. 5

   Nobody else is named closer

   If a colleague is named nearer to the relevant sentence, the review counts for them instead. “My guide David was a skilled cave diver” is evidence about David, even if the review thanks the owner at the end.

Not everything comes from Google

A good deal of what we know about instructors in the United States and Mexico came from ScubaBoard threads, r/scuba and r/cavediving, InDEPTH and TripAdvisor rather than from a dive centre's Google page — the cave community talks about instructors in forums more than it reviews them on Maps. Those sources are held to a looser test than a Google review, deliberately. A Google review arrives in bulk and nobody has looked at it, so it has to prove both that it is about this instructor and that it names a technical subject. A cited source has already passed two human filters: somebody chose that thread as relevant and chose that quote as evidence about this person. So a plain recommendation — someone answering “who should I train with?” in a cave diving forum with a list of names — counts, even though it names no technical subject at all. The thread it came from is the context, and that is the thing a keyword test cannot see. One thread counts once, however many quotes it yields, and a quote about somebody's open water teaching still does not count.

Until September 2026 that forum evidence only ever arrived incidentally, as a side effect of somebody sitting down to write a synthesis and citing what they had read. Everybody else got nothing — not because no forum evidence existed, but because nobody had gone looking. Of 95 ranking instructors, 23 carried any, and they were almost exactly the people whose profiles had been written from forums in the first place. Natalie Gibb, named in ten separate ScubaBoard and Reddit threads as the cave instructor to train with in Quintana Roo, counted two, because Google Maps happens to hold two reviews naming her. We now search ScubaBoard and Reddit for every instructor on the site as a standing part of each refresh, rather than waiting for the evidence to turn up.

A search result is not evidence on its own, and four ways it can lie are filtered out before anything is counted. It can be a different person — one instructor's name returned ten threads from a country-music fan forum — so Reddit results are restricted to diving communities. It can be the instructor's own forum signature, which lists his certifications and his rebreathers under a post he wrote about something else, and reads like praise to any keyword test. It can be a thread about an accident, a death or a lawsuit, where a name is not an account of being taught. And it can be a complaint: a thread titled “Disappointment with” somebody is not added to that person's total. Nothing is ever subtracted either — the count is a volume of broadly positive evidence, and a complaint is recorded and set aside rather than turned into a penalty. Every rejected result is kept with the reason it was rejected, so a rule that is throwing away good evidence shows up as a pile of good evidence rather than as a number that is quietly too low.

One consequence is worth stating plainly, because it shapes what you see. Forum discussion in English is dominated by cave diving in Florida and Mexico, so the sweep found far more there than elsewhere: it accounts for around half of the technical evidence we hold on United States instructors and about a sixth of what we hold on instructors in Thailand. That is partly real — those scenes genuinely are discussed more — and partly a limit of where we are looking, since an instructor in Indonesia or Thailand is more likely to be talked about in a Facebook group, or in a language we read poorly, than on ScubaBoard. Read a low count as thin evidence, not as a poor instructor.

What the aspect tags are, and are not

The short labels on a profile — patient, explains the why, go-to for sidemount — describe what an instructor is like, drawn from what reviewers actually say, and readers can vote on them. They are a description, not a score, and they do not determine ranking. We used to order listings by them and it produced results that made no sense: an instructor whose reviews had been read closely outranked one with five times as many reviews that nobody had read yet. Counting the reviews measures evidence; counting the tags measured how much reading we had done.

How a synthesis is written

• It is written from the review text, and the quotes it rests on are stored with it.
• Where reviewers disagree, or where a review raises a real criticism, the summary says so. A page where every listing reads as uniformly excellent is a page nobody should trust.
• Thin evidence is labelled as thin. An instructor named once is described as a lead, not as an established picture, and some instructors deliberately have no synthesis at all because the only coverage of them is a credential rather than an account of their teaching.
• A synthesis is never written or edited by the person or business it describes. Listing owners can edit their own contact details, courses and prices; the synthesis is locked at the database level, not merely hidden in the interface.

Where this method is weak

• Language. The subject terms are mostly English, with common German, Spanish and French equivalents added. Coverage is not equal, so an instructor whose reviewers write in another language will have a count that is a floor rather than a measurement.
• Multi-person reviews. Deciding who a sentence is about by how close a name sits to it is a rule of thumb. “X was our guide and Y our photography instructor” is resolved correctly; more tangled sentences are not always.
• Readers use “cave diving” loosely, and we count what they write. A guided cenote trip is usually a cavern dive — inside the daylight zone, open to any certified diver — but people who have just done one very often describe it as cave diving, because that is what it felt like. Reviews saying “we went to Dos Ojos cave diving”, or mentioning that the shop offers a cave course, count the same as a review from someone who actually took one. Across the whole corpus at least a quarter of counted reviews describe a dive rather than a course, and in the Riviera Maya, where guided cenote tourism is the main business, it runs higher. The practical effect is that a centre running recreational cenote trips can carry a similar count to one teaching full cave. We count it that way on purpose — cave and cavern guiding is genuinely part of what this directory covers — but a high count is not by itself evidence that a centre teaches technical diving. The courses a centre actually publishes are the better guide to that, and they are listed on its page.
• Forum threads name people, not shops. Somebody asking “who should I train with in cave country?” is answered with names, so the evidence arrives attached to an instructor and reaches a dive centre only through its roster. That works — it is how several one-instructor operations have any count at all — but it means a listing whose roster is out of date is also missing evidence it has earned. If you teach somewhere we have not linked you to, tell us and both listings improve.
• The most technical operators are the least visible. A freelance cave instructor does not run a storefront, so there is often no Google Business listing to find at all. Twenty-six dive operations in Mexico — among them several whose names are simply Cave Explorations, Cave Ha Diving, Advanced Diver Mexico, Sabine Technical Diving — have no Google place we can match, and therefore no Google reviews, however well-regarded they are. It is the same shape of gap as the forum sourcing above: the deeper into technical diving a listing sits, the worse Google represents it.
• Coverage. Most listings have no technical reviews on file at all, either because none exist or because we have not fetched that centre yet. A low count means we found little, which is not the same as there being little.
• Volume favours the established. A shop open for fifteen years accumulates more reviews than an excellent one open for two. The count is a measure of evidence, not of quality.