The added exertion of swimming alone could easily reduce that figure by half. Air consumption is difficult to measure, but the average tidal volume (the bit we breathe in and out during a normal breath cycle) of the human lung is 0.5 litres, and the average breathing rate of an adult is 12-20 cycles per minute, and so in theory, it would be possible to breathe from these devices for 12.5 minutes.īut those figures only apply to healthy adults at rest. They are all promoted as a ‘safe’ alternative to ‘expensive’ scuba diving, with no training required.Ī half-litre tank pressurised to 200bar means you have around 75 litres of air to breathe before you hit 50bar. Many commentators on dive forums have pointed out that they are ‘deathtraps and lawsuits waiting to happen.’ Experienced scuba divers would have no problem using these devices safely, but that is not necessarily the market at which these devices are being targeted. Neither product comes with a depth gauge. The maximum depths for each product are given as 50m and 20m for trained scuba divers, while the recommended limit is 10m in both cases. The MiniDive’s user manual, for example, states that you should ‘NEVER stop your respiration during your descent or ascent.’ But not until page six! From the MiniDive sales websiteīoth products set a maximum depth limit of three metres for uncertified divers. The manufacturers explain at some length on their websites that there are safety considerations to be taken into account, and that rules and procedures must be followed. If it falls out of your mouth, your air supply is gone. The MiniDive’s harness will at least help to prevent its loss, but the Scorkl has no security straps. It has a regulator and mouthpiece attached directly to the cylinder, with a pressure gauge mounted on the mouthpiece which can only be read by removing the device from your mouth. The Scorkl is – basically – a Spare Air cylinder with a different label.

The Mini-dive comes with a small harness worn around the chest, with a first and second stage regulator similar to a scuba system, and an attached pressure gauge. The MiniDive (Indigogo) and Scorkl (Kickstarter) are small, 0.5-litre tanks with an attached regulator and pressure gauge. Two crowdfunded compressed air ‘snorkelling’ devices have been circulating on social media, causing an outpouring of shock and horror among the dive community. Promotional image of the controversial Scorkl Revillagigedo Archipelago & Guadalupe Island.

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