Quick Answer: The cache did not move - the vegetation did. Between June and September, undergrowth in temperate woodland typically doubles in height and density, ground cover fills the gaps you originally walked through, and leaf canopy is at its thickest, which degrades GPS accuracy at the same time. A hide that was in plain sight in early summer is now behind 30 inches of growth, and your approach path no longer exists.

You have the coordinates. You have found this one before. You are standing at ground zero and the arrow is spinning, and after twenty minutes you start seriously considering that someone muggled a cache that has been logged as found four times this month. Before you post that note - the problem is almost certainly seasonal, and it is more predictable than it feels.

What actually changes between an early-summer find and a late-summer one?

Undergrowth peaks in late August, not July. Most people assume the woods are at their most overgrown at midsummer. In practice, herbaceous ground layer biomass in temperate woodland peaks in the last weeks of August after a full season of accumulation. Bramble, nettle, bracken, and goldenrod are all at maximum extent right now. A cache tucked at the base of a tree with clear sightlines in June can be under two and a half feet of growth in September.

Canopy density is also at maximum, and that is a GPS problem. Satellite signal has to pass through foliage, and dense leaf cover both attenuates the signal and creates multipath error where the signal bounces before reaching you. Under full canopy, consumer GPS accuracy commonly degrades from around 10 feet to 30 or even 50 feet. Your device is not broken, it is guessing - and it will confidently show you an arrow while doing it.

Your approach route has quietly closed. This is the underrated one. The first time you found the cache, you probably approached from a specific direction because that was the gap. Gaps fill. If you now approach from a different angle because the old one is impassable, you are seeing a completely different geometry, and the hide that made obvious sense from the north makes no sense at all from the west.

And your own memory is working against you. You remember finding it, which produces a strong conviction about where it was, and that conviction stops you searching the places you have already mentally ruled out. Returning finders often perform worse than first-timers on overgrown caches for exactly this reason.

Why does your GPS get worse in exactly the places you need it most?

Because the geometry that helps you in open ground works against you in woodland. Your receiver wants satellites spread across the sky. Under canopy, the low-elevation satellites near the horizon are blocked by trunks and foliage, so your device ends up using a cluster of high-elevation ones. That clustering weakens the position fix in the horizontal plane, which is precisely the plane you care about.

Multipath makes it worse and looks like precision. When a signal bounces off wet foliage or a rock face before reaching your device, it arrives late, and the device interprets late as further away. The result is a position that is confidently wrong. A displayed accuracy of 12 feet under heavy canopy frequently means real-world error two to three times that.

Wet leaves are meaningfully worse than dry ones. Late summer humidity and morning dew both increase signal attenuation. Caching the same wooded spot at 7am after a damp night and at 3pm on a dry afternoon can produce visibly different arrow behavior.

The practical fix is to stop trusting the arrow at close range. Walk in to about 40 feet, then put the phone away and read the terrain. Look for the hide, not the number. Experienced cachers describe this as the switch from navigation to searching, and the people who struggle most are the ones who never make the switch.

5 Mistakes That Turn a 20-Minute Search Into a DNF

1. Circling ground zero without ever leaving it. The single most common failure. If the arrow is wrong by 40 feet, orbiting the arrow keeps you inside a wrong circle forever. Deliberately walk 60 feet out in one direction, stop, and come back in on a straight line. The approach itself reveals hides that the orbit never will.

2. Searching at the height you searched last time. Growth changes what looks reachable. A hide at knee height in June is at ankle height inside a thicket in September, and your eyes are scanning the wrong plane.

3. Reading the hint before reading the terrain. Hints are written from the hider’s perspective in the season they hid it. Behind the fallen log means something different when the log is buried in bracken. Read the terrain first, then let the hint confirm.

4. Ignoring the recent logs. Four found-it logs this month with no comment usually means it is genuinely there and genuinely findable. Two logs mentioning overgrown or took a while is the strongest possible signal that this is a vegetation problem, not a missing container - and it should change your search method, not your confidence.

5. Dressing wrong and giving up early. A huge fraction of September DNFs are actually comfort failures. Nettle, bramble, and ticks are all at seasonal maximum. In shorts, you search for eight minutes and then decide it is not there. In long trousers and sleeves, you search for thirty and you find it. The gear determines the outcome more than the skill does.

What is the right way to search a cache you know is overgrown?

Start by widening rather than narrowing. Accept a 50-foot uncertainty radius from the outset. Stand at ground zero, pick four compass directions, and walk each one out and back. This takes six minutes and covers more ground than half an hour of circling.

Search from low and look up. Crouching changes your sightlines completely. Most hides are placed at or below waist height, and from a crouch you see under the growth layer rather than at it. Cachers who kneel find things that cachers who stand walk past four times.

Look for the unnatural line. Nature makes very few straight lines and almost no perfect right angles. Under vegetation you are not looking for a container, you are looking for a straight edge, a uniform curve, or a color that does not belong - a flat green that is slightly too flat, a stack of sticks that is slightly too deliberate.

Feel where you cannot see. In dense late-summer growth, hands beat eyes. Sweep the base of likely hosts - tree roots, wall bases, fence posts - with a gloved hand rather than trying to see into them. Gloves are non-negotiable in bramble and nettle season.

And give yourself a hard stop. Set 25 minutes. If you have not found it, log a DNF with a genuinely useful note about conditions and come back after the first hard frost knocks the growth down. That note helps the next person and the cache owner far more than a silent retreat does, and there is no shame in a seasonal DNF - it is information, not failure.

FAQ: Seasonal Geocaching Questions, Answered

Should I log a DNF if I am fairly sure it is just overgrown?

Yes, and say so explicitly. A DNF that reads could not access, heavy bramble, cache likely fine is genuinely useful data. It tells the owner there is no maintenance issue and tells the next cacher what to bring. A silent non-log leaves everyone guessing, and a string of unexplained DNFs can get a healthy cache disabled unnecessarily.

When does the vegetation actually clear enough to go back?

In most temperate regions, the useful window opens after the first two or three hard frosts, which knocks the herbaceous layer down fast - typically late October into November. Woodland caches are often easiest between November and March, which is why experienced cachers keep a saved list of overgrown DNFs specifically for winter.

Does downloading offline maps or using a different app help with accuracy under canopy?

Offline maps help with navigation but not with position accuracy - the limitation is satellite geometry, not data. What does help is letting the device sit still for 60 to 90 seconds at ground zero so it can average a fix rather than chasing you, and using a device that supports multiple constellations rather than GPS alone.

TL;DR:

• Undergrowth peaks in late August, not midsummer - the cache is likely buried in growth that did not exist in June.
• Dense canopy degrades GPS accuracy from roughly 10 feet to 30 or more, so the arrow is confidently wrong at close range.
• Walk out and back in on straight lines rather than orbiting ground zero.
• Crouch and use gloved hands; in September, touch beats sight.
• Long sleeves and trousers change your outcome more than technique does, because they determine how long you are willing to search.

The cache you cannot find today is very often the cache you will find in four minutes in November. Log the DNF honestly, note the conditions, and put it on your winter list.