Hügh

Groundspeak, Inc., aka. Geocaching HQ. Uh, money. I almost guarantee that the income from Premium Members who benchmark is nowhere near enough to pay for servers, hosting space, and salar(ies) of the staff who keep an eye on the systems. Don't get me wrong, I am equally as upset about Benchmarking disappearing from the site. However, I have to be sympathetic to HQ's interests here: I would not want to have to be responsible for maintaining the (spaghetti, insecure, outdated) code powering the Bechmarking site.

I assume the cache doesn't expire stuff, since the cache "will continue to populate." As in, over time, the percentage of all logs that are in the cache will increase.

Possibly (definitely) related: the big change to the Pocket Query infrastructure that was announced a couple days ago?

In comparison, over 1.5 million logs (= GL18J2NCN_31 - GL18GAPQ2_31; this probably isn't 100% accurate but it should be close enough) have been posted on the main Geocaching.com site.

I think that a benchmark can be either a survey marker or a trigonometrical point (or even a lighthouse). But in particular it is a marker point placed by the US Geological Survey for the purpose of geodetic surveys. For instance, all (?) of the mile markers along the Can/US border are benchmarks. Other than Peace Arch, Monument 74 is the only one I’ve visited.

I should clarify: the OP is more than welcome to learn how to tree/rock/whatever-climb. I'm not trying to gatekeep this sport. But because it's being presented as "I want to find a couple caches that are high up in trees, where can I buy rope?", I am anxious for the OPs safety. It is not the right mindset here. The question they really should have asked is "where can I learn how to climb trees/rocks/whatever safety." OP: Learn how to climb rocks/trees/whatever in a rock/tree/whatever-climbing class. Use the gear provided by instructors. Make sure you are comfortable. Talk to the instructors. They will be more than happy to help you find rope, harnesses, etc. They are the experts, not random strangers on a Geocaching forum.

For one, rock-climbing courses are generally more accessible than tree-climbing courses. But also, that's not the point. It is in no way a waste of time and money. My goal for the OP is for them to: Get comfortable with ropes, harnesses, belay devices, etc. in a safe, indoor setting before going outside. If they can find anything advertised as "tree-climbing lessons"; great—but I doubt it. Rock climbing lessons are similar enough that they will accomplish this same goal. Take a fall themselves or watch someone take a fall and realize that maybe climbing (anything) is really, really, dangerous. It is not a skill that can just be picked up for the sake of finding some caches; no, it needs to be learned separately. Actually talk to people (face-to-face!) about their goals and reasons, instead of asking random faceless strangers on the internet. Even if climbing gym staff aren't experts on tree climbing, they will be able to say smart things (and possibly even talk OP out of this.)

Suggestion: find a local rock-climbing gym and get some lessons on how to use the gear, first. (Please? I have been climbing for nearly ten years and still I manage to mess things up. When you introduce specialized equipment it becomes very, very easy to injure yourself.) Find someone that climbs.

Yes. Open the listing, tap "X reviews" (beside the star rating at the top) and then "rate and review" under your name near the top.

As long as any additional physical or virtual stages are added as (hidden) waypoints to the cache listing, I doubt the Reviewers would take issue.

Yes. See https://project-gc.com/Tools/MapCompare?profile_name=Breaktrack&nonefound=on&onefound=on&bothfound=on&ownfound=on&hidden_fromyyyy=2000&hidden_frommm=1&hidden_fromdd=1&hidden_toyyyy=2002&hidden_tomm=12&hidden_todd=31&submit=Filter.

...also, there's multiple physical stages with info for the cartridge. And, the final is a gadget cache requiring special tools/equipment.

I have seen Challenges that require you to solve a puzzle on the cache page to determine an lock combination. That, I think, is allowed. Not sure how that works with Bonus caches, though. I guess you could technically pick or brute-force the combination, so, you might be able to argue that it is possible to open the cache without finding the series. Those guidelines apply to the Challenge portion only, not to the finding portion. Also, as pointed out above, you technically don't need to find the series; you can open and sign the cache without breaking the ToS (getting the combo from a friend) or damaging the container. According to CacheDrone, Bonus/Challenge trumps Wherigo, although I personally disagree a bit with that.

What is more important than: ...is good training from certified professionals. I have been rock-climbing for over ten years. I am not kidding when I say that you could easily kill yourself using "safe gear", just by using it wrong. Are a couple geocaches risking your life for?

“This cache is in my front lawn. But being my property I will charge a $1000 fee for access.” Hence only “small” fees to government or non-profits are permitted. It’s a ballpark figure that Reviewers have agreed upon. I cite:

There are a couple (old) threads discussing this already. tl;dr: The idea seems to be that elevation is disregarded. Assume the earth is (locally) flat.

If I recall correctly, the one at Toronto Pearson has a geo-fence of 2km. It was mostly airport-related trivia questions (ie. "What is the former name of Toronto Pearson?") These, to me, don't "feel" like Adventure Labs. However, I suppose that they don't indisputably violate any of the guidelines:

…it can automatically launch a trackable page, and cachers can discover each other? Why bother with NFC, automatic logging, ...? A whole cache type...?

Yup, you've got a dot with characters on both sides. That is, apparently, intended.

If you've already "unlocked" the stage, the stage is permanently unlocked for you and can be completed from anywhere. Others will still need to visit GZ first.

smiley i want mah smiley gimme smiley smiley smiley smiley

You can't discover your own trackables. "Discovering" adds no miles to the odometer. "Visiting" a cache, does.

Yes, as long as the CO has permission from the land owner, that should be allowed.

To display on the Browse Map, on the left panel, select “Pocket Queries” and then click the appropriate query. To see them in the Official app, tap Lists. The query should be somewhere there. You can then save offline, etc. as if it were a bookmark list.