Fathom strategy: a full hold is the slowest way home
Fathom has no engine that lifts you. The submarine floods to sink and blows its tanks to rise, and everything you put in the hold is weight the tanks have to beat. That single fact decides how much you should dig, which metals are worth the climb, and why the richest seams are the deepest ones.
You cannot fly. You can only float.
The hull displaces 1000 kg of water and weighs 700 kg dry, so you have 300 kg of lift and never any more. Ballast is how you spend it: flood the tanks and you sink, blow them and you rise. There is no thrust that pushes you upward.
Cargo eats that same 300 kg. At 150 kg in the hold you climb at half speed. At 300 kg you do not climb at all — you sit on the floor of the shaft you dug, blowing tanks that have nothing left to give. The game will not stop you loading yourself into that position, and the first time it happens is the moment Fathom makes sense.
Load 180 kg, not 300
The temptation is to fill the hold, because a full hold looks like a good dive. It is not. The climb slows as the hold fills, so the last kilograms are carried at the slowest speed of the whole trip — you pay the most time for the cargo that earns the least.
Work out the money per minute for every possible load and the answer is about 180 kg, well short of the ceiling. What is surprising is that the answer does not move: 180 kg is the best load at 200 m and still the best at 800 m, in every boat. The deep does not ask you to carry more, it asks you to make the same trip further.
The lightest, richest metal is the exception. A hold of neodymium is worth stopping earlier still, nearer 120 kg, because it is hard to cut and light to carry, so the digging time is what costs you rather than the climb.
The deeper the metal, the more it is worth
Seven metals, laid down in the order you already rank them. Their depths overlap, but on average each one lies deeper than the last. The number that matters is what a kilogram is worth, because kilograms are the thing you are actually rationing.
| Metal | Weight | Value | Per kg |
|---|---|---|---|
| Iron 76–268 m The Shelf | 20 kg | $18 | $0.90 |
| Copper 76–492 m The Shelf, The Ribs | 16 kg | $34 | $2.13 |
| Tungsten 276–492 m The Ribs | 14 kg | $62 | $4.43 |
| Silver 276–700 m The Ribs, Blackreach | 10 kg | $110 | $11.00 |
| Gold 500–860 m Blackreach, The Foundry | 6 kg | $240 | $40.00 |
| Platinum 500–860 m Blackreach, The Foundry | 5 kg | $400 | $80.00 |
| Neodymium 708–860 m The Foundry | 4 kg | $640 | $160.00 |
Platinum is worth nearly ninety times iron per kilogram and weighs a quarter as much. Once you have seen this table, iron stops looking like treasure and starts looking like what it is: the thing that fills your hold before you reach anything good. On the Shelf it is worth taking because it is what there is. Below that, dig past it.
There is one use for a heavy, cheap metal, and it is not money. Iron is excellent diving weight. Take some on the way down to sink faster, then drop it before you climb.
Tungsten is the one to watch. It is worth nearly twice what copper is, but it is genuinely hard to cut: a piece takes over half again as long to drill, so for the battery it burns it pays only a little more than copper.
Precious stones are rare, light and worth a fortune
Three precious stones lie in the rock alongside the metals, scattered one at a time and never in veins. Like the metals, the deeper the stone, the more it is worth.
| Stone | Size | Value | Per carat |
|---|---|---|---|
| Emerald 76–492 m The Shelf, The Ribs | 15 ct | $260 | $17 |
| Ruby 500–700 m Blackreach | 8 ct | $1,200 | $150 |
| Diamond 708–860 m The Foundry | 5 ct | $6,000 | $1,200 |
They are genuinely rare. A whole ocean holds about fifteen: ten or so emeralds, three rubies and one or two diamonds. That makes them something you find rather than something you farm, and the one cargo you never have to think about, because a stone is measured in carats: the biggest is a 15 carat emerald, three grams. An emerald is worth more than a piece of gold and weighs a two thousandth of it. A ruby is worth as much as three pieces of platinum. A diamond is worth more than nine pieces of neodymium, and you could carry a thousand of them inside one.
If you see one, it is worth a detour. You will not see many.
Drop cargo. It is a tool, not a defeat.
The DROP CARGO button exists because the law is unforgiving and the game expects you to use it. If you are stuck at the bottom of a shaft, dropping the heaviest thing you are carrying is what gets you home. Dropped cargo is lost, but a dive that ends on the seabed loses the whole hold.
Get in the habit of dropping iron the moment you find something better. Room in the hold is not the constraint — the 300 kg is — so trading 20 kg of iron for 6 kg of gold is almost always right.
Magma is the one thing that will not forgive you
The orange seams in the deep are not metal. Breaking into magma damages the hull, and the hull is the one meter that does not refill on its own at the surface. Everything else is a running cost; hull is a budget for the whole boat.
Magma is easy to identify and easy to avoid, and it is placed where you would most like to dig. Take the long way round.
What actually runs out
Three meters run down and they do not fail in the way you expect. On an ordinary dive to the bottom and back through tunnels you have already cut, air and battery are barely touched — a deep run home uses only around a tenth of each. The thing that ends dives is the law and the hull.
Battery becomes real the moment you stop using existing tunnels and start cutting fresh rock, because digging is what drains it. Cutting a brand-new shaft to the deep in the starting boat runs the battery flat at a little over 200 m. That is not a bug, it is the reason to buy a bigger boat: you are buying the right to open new ground rather than re-use your own.
Air is a clock rather than a wall. It refills at the surface, so it punishes dithering, not depth.
Four regions, and they are places
The ocean is 880 m deep and divided into The Shelf, The Ribs, Blackreach and The Foundry. Each region is richer than the one above it: a stretch of the Foundry holds around seven times the metal value of the same stretch of the Shelf. The caverns and landmarks are placed rather than scattered, and the deepest of them are small motherlodes of silver, gold and platinum, so the map is worth learning. Your tunnels persist between sessions, which means the shaft you cut today is the commute you get tomorrow.
The fleet is the progression
Nine boats, from the Minnow you start with up to hulls that cost thousands. They trade against each other rather than simply getting better: more air, more cargo, more battery, a stronger lamp, a faster drill. The drill matters more than it looks, because the hardest rock cannot be cut at all below a certain drill rating — some ground is closed to you until you own the boat that opens it.
Buy for the job. A bigger hold is worth very little while 300 kg of lift is what limits you; more battery and a better drill are what let you reach new ground.
The short version
- You have 300 kg of lift, forever. Cargo spends it.
- Aim for 180 kg, not a full hold. A full hold does not rise.
- The deeper the metal, the more it is worth: iron $0.90 a kilo, gold $40, neodymium $160.
- Always take a precious stone. They weigh grams, not kilos, and a diamond is worth $6,000.
- Carry iron down as diving weight, then drop it.
- Dropping cargo is a tool. Use it before you are stuck, not after.
- Magma damages the hull, and the hull does not come back.
- Battery is what stops you cutting fresh rock. Buy the drill.
- Your tunnels persist. Today's shaft is tomorrow's commute.
Ready to put it to work?
Play Fathom →More games: the arcade · Ballast · all Zamborin games · all guides