Honeytoe's Underground Fields

Concept 2026 — Helsinki, Finland

Food from within the earth, for the world.

The world's first geothermal spiral garden — carved deep
into Helsinki's bedrock. Thousands of hectares of cultivated area
without sunlight, without dependence on weather.

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Why this matters

The world is hungry.
There is no reason.

Over 700 million people suffer from hunger this year. At the same time, a third of all food produced is wasted. The problem is not production — the problem is dependence on weather, fossil fertilisers and fragile supply chains.

Climate change is making things worse. Droughts, floods, heat waves — traditional agriculture is most vulnerable at the very moment it is needed most.

The Honeytoe solution: take farming underground, where temperature is stable, water circulates, energy rises from the deep — and the harvest grows year-round regardless of what happens on the surface.

733M

people hungry
in the world today

33%

of the world's food
is wasted

+2°C

temperature rise threatens
to reduce yields by 25%

4800 ha

of cultivated area
across three spirals

How it works

Three innovations.
One system.

🌀

Geothermal Spiral

Tunnels are excavated to 2 km depth at a 1–2% gradient. The spiral shape means that heat rising from depth distributes naturally into different zones — from tropical plants to cool-climate vegetables.

8×8M TUNNELI · 1-2% KALLISTUS · 100–200 KM TUNNELIA / SPIRAALI

💧

Closed Loop

Water and nutrients are fed from the top and flow by gravity through the entire spiral. Plants take exactly what they need. At the bottom, water is purified in a collection basin and pumped back up. Zero waste.

HYDROPONICS · 95% LESS WATER THAN CONVENTIONAL FARMING

⚡

Energy Self-sufficiency

Deep in the bedrock, temperature reaches +60–70°C. Heat pumps convert this into energy. Plant LEDs in upper levels are supplemented with fibre-optic sunlight cables. Goal: a net-zero farming system.

GEOTHERMAL + LED + FIBRE-OPTIC SUNLIGHT · GOAL: NET ZERO

🅿️

Surface Layers

At 0–50 m depth: parking, storage and distribution terminals. Cars off the streets, logistics underground. These levels can be partly financed by selling parking spaces.

PARKING · STORAGE · COLD CHAIN · DISTRIBUTION TERMINALS

🤖

Automation

Harvesting, planting, irrigation and nutrient adjustment are handled by robots. Sensors monitor every plant's growth in real time. Human work shifts to planning and development.

ROBOTICS · IOT SENSORS · AI-OPTIMISED GROWTH

🌍

Scalable Model

Helsinki is the prototype. The same concept works anywhere there is bedrock — Scandinavia, Canada, Japan, South Korea. Excavated rock is sold as construction material, covering part of the costs.

REPLICABLE MODEL · EXCAVATED ROCK = CONSTRUCTION MATERIAL

Structural zones

From the surface
to the depths.

0 – 50 m

Surface — Infrastructure

Parking, storage, distribution terminals, cold chain. Cars off the streets, logistics efficiently underground.

+8–12°C · Cold storage

50 – 300 m

Cool Zone

Leafy greens, herbs, lettuce, spinach, kale. Northern climate varieties. LED lighting + fibre optics.

+10–20°C · Herbs, lettuce, leafy greens

300 – 800 m

Temperate Zone

Tomatoes, cucumbers, peppers, courgettes, berries. Potatoes and root vegetables in growing medium on the spiral floor.

+20–30°C · Vegetables and fruit plants

800 – 1400 m

Warm Zone

Tropical plants — banana, mango, papaya, ginger. Mushroom cultivation makes effective use of heat and humidity.

+30–45°C · Tropicals + mushrooms

1400 – 2000 m

Geothermal Zone

Heat exchangers, energy production. Hot water is pumped upward to heat the upper zones. Nothing is grown here — this is where energy is born.

+50–70°C · Energy production

TUNNEL SIZE: 8×8 METRES
GRADIENT: 1–2%
SPIRAL DIAMETER: 500–1500 M
DEPTH: 2000 METRES
TUNNEL PER SPIRAL: 100–200 KM

Scale & Numbers

The numbers speak.

4 800

hectares of cultivated area
across three spirals

2M+

people fed
per year

350 km

of tunnel in total
three spirals

50–100
Mrd€

total investment
all three spirals

COMPARISON: Olkiluoto 3 nuclear plant = €11 billion · Helsinki Länsimetro = €1.2 billion · Excavated rock (~50–100 M m³) sellable as construction material → value €500M–2Bn · Parking levels can be financed by parking sales

Timeline

The path from idea
to reality.

2026–2028 · Now

Concept & Community Building

Publishing the idea, building a community of interested researchers, engineers, investors and policymakers. Commissioning first technical studies.

2026–2030 · Near future

Prototype — Small pilot at 50m depth

A small pilot tunnel (2 km long) is built at 50 m depth to test the growing system, water circulation, LED lighting and automation. Goal: prove the concept works.

2030–2040 · First spiral

Full-scale Spiral I — Helsinki

First Ø500m spiral to 500m depth. Partly financed through parking and storage sales. EU food security programme support. Commercial operations begin.

2040–2060 · Expansion

Three Spirals, Full Depth

All three spirals (Ø500m, Ø1000m, Ø1500m) reach 2 km depth. Geothermal energy fully operational. The system covers Finland's entire plant food needs.

2060+ · Global

Replication Model for the World

The Helsinki model is licensed to other countries. Scandinavia, Canada, Japan, Korea — bedrock exists everywhere. The Honeytoe spiral becomes the global food production standard.

Join us

This idea needs you.

Are you an engineer, researcher, investor, politician or simply someone who wants to save the world? Everyone is welcome. The idea is open — let's develop it together.

Honeytoe's Underground Fields
Honeytoe's Underground Fields
Helsinki, Finland

Food from within the earth, for the world.

The world is hungry.There is no reason.

Three innovations.One system.