Debunking the claims:
1. “WaterLight is eco-friendly, being 100% recyclable and waterproof.” *The magnesium block in the device will be used up in the process, and magnesium chloride salt and caustic Sodium Hydroxide (lye) will be produced. For the magnesium to be recyclable, you’d need to send the salt and the lye to a chemical plant. The impression given in the video is that the device is used in a less developed location. It is unlikely there will be a chemical plant there, hence the 100% recyclable claim is bogus.*
2. “So, it’s durable and sustainable, regardless of where it ends up.” *Recovering the magnesium from magnesium chloride will cost a lot of energy, not to mentioned the energy involved in transporting the magnesium chloride to the chemical plant and the energy for running the equipment in the plant. It is a poor use of magnesium and it cannot be considered as sustainable.*
3. “This incredible lantern utilizes the ionization of an electrolyte composed of saltwater, which converts the magnesium inside the lantern.” *What BS is this? The saltwater is the only electrolyte and it is already ionised, while at the sea. There is no need to put it into this device beforehand.*
4. “This small yet mighty circuit makes it possible to extract around 500 watts for each liter of water!” *’Watts’ is not the correct unit to indicate the amount of energy you can draw from the device. It should be in joules/kilojoules and sometimes milliampere hours together with the voltage. Also, the electrical energy comes from the magnesium, not from the saltwater, which is just there to conduct the electricity. Using ‘watts’ or its equivalent, joules/sec, and saying the energy come from the saltwater just indicate the narrator doesn’t understand the shit he’s saying.

A magnesium-copper battery like this will generate about 2.7 volts. If the 500 watts figure is correct, it means the device has 185 000 milliampere hours of charge. A current premium smartphone has 5000 milliampere hours of charge, which means this device has 37 times the charge of a premium smartphone! That’s hard to believe.

5. “Waterlight’s possibilities are endless.” *No, it’s not. After the 45 days, the lantern will stop working and it is thus not “endless”. It will require a major replacement of the magnesium inside to make it work again, but how will you easily find a block on magnesium in a less-developed location? A solar-rechargeable lantern is so much more re-usable.*

6. “It can benefit off-grid communities in need of an electrical source to supply light, charge a cell phone, or listen to a radio.” *While the device can charge a cell phone, the magnesium will be quickly used up and the device’s life will be greatly shortened if used for this purpose.*

7. “…and education – for turning on a computer or a television.” *If you have the electricity to turn on a computer or a television, why would you need this weak lantern to light up your surroundings?