Sources

The animals and the scams

Landmarks on the way down

• 120 m, giant siphonophores drift here: Longest bioluminescent animal, Guinness World Records
• 200 m, most sunlight is gone: How far does light travel in the ocean?, NOAA Ocean Service
• 332 m, deepest scuba dive ever: Ahmed Gabr breaks record for deepest scuba dive, Guinness World Records (2014)
• 564 m, deepest dive by a bird, an emperor penguin: Deepest dive by a bird, Guinness World Records
• 610 m, sperm whales routinely hunt this deep: Sperm whale, NOAA Fisheries
• 1,000 m, no sunlight at all from here down: How far does light travel in the ocean?, NOAA Ocean Service
• 3,800 m, the Titanic rests here: Titanic bow, NOAA Ocean Exploration
• 4,000 m, the abyss begins: Layers of the ocean, NOAA
• 6,000 m, the hadal zone begins: the deepest trenches: Layers of the ocean, NOAA
• 10,935 m, challenger Deep, the deepest point in the ocean: The depth of the Challenger Deep (2021 study), NOAA

The questions

Every message, call, shop and link in the challenges is made up for practice, using the patterns real scams follow. The hard-mode attacks (fake CAPTCHAs, QR code scams, invoice redirection, MFA fatigue, account takeover, fake login pop-ups, fake search ads, callback phishing, fake recruiters and SIM swaps) are all real techniques; the examples of them are invented. The brands (Northway Bank, ParcelPost, HM Tax Office and the rest) are invented, and the phone numbers come from the ranges Ofcom keeps aside for fiction, so none of them is real.

The depth gauge

The gauge shows typical open-ocean values: pressure rises about one atmosphere every 10 metres, sunlight fades to around 1% by 200 metres and is gone below 1,000 metres, and deep water below about 200 metres averages about 4 °C. Real water varies by place and season. The sound, when you turn it on, is made live in your browser.

• How does pressure change with ocean depth?, NOAA Ocean Service
• How far does light travel in the ocean?, NOAA Ocean Service
• What is the deep ocean like?, NOAA Ocean Exploration
• Bioluminescence, Smithsonian Ocean

Photos

• Reef sharks in sunlit water (the surface): photo by Dennis Hipp, CC0
• The mimic octopus: photo by Rickard Zerpe, CC BY-SA 2.0
• The giant siphonophore: photo by Catriona Munro, Stefan Siebert, Felipe Zapata, Mark Howison, Alejandro Damian-Serrano, Samuel H. Church, Freya E. Goetz, Philip R. Pugh, Steven H. D. Haddock and Casey W. Dunn, CC BY 4.0
• The hatchetfish: photo by NOAA/NMFS/SEFSC Pascagoula Laboratory; collection of Brandi Noble, Public domain
• The beluga whale: photo by Versions111, CC BY 4.0
• The deep‑sea anglerfish: photo by Emőke Dénes, CC BY-SA 4.0

Photos are seen through the glass lens, so they are cropped to a circle and gently distorted at the edge; two studio photos get a deep-water tint, and the aquarium photo of the beluga is colour-graded to deep-water green. Share-alike photos stay under their original licence.

Reporting scams in the UK

• Report Fraud (which replaced Action Fraud in December 2025), or call 0300 123 2040. In Scotland, Police Scotland on 101.
• Forward scam texts to 7726, free on most UK networks: What to do about a scam call, text or message, Ofcom.
• Forward scam emails to report@phishing.gov.uk: Report a scam email, NCSC.
• Call 159 to reach your bank's fraud team: Call 159, Stop Scams UK.
• Money paid back to scam victims in 2025: Annual Fraud Report 2026 (figures for 2025), UK Finance.