Watchly Safety Review

World's Largest Super Soaker

Mark Rober

8:05 · 52.8M views · July 11, 2017

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Some ConcernsReviewed June 2026

1Moderate Concern

4Minor Flags

1No Issues

This video is safe for most kids and doubles as a genuinely engaging engineering lesson wrapped in a fun water-fight premise. The highlight is a real interview with Super Soaker inventor Lonnie Johnson, giving the video surprising educational depth, though parents should note the gun operates at pressures far beyond safe backyard use and is presented with some destructive flair.

Content Breakdown · 6 Categories

Bullying, Cruelty & DiscriminationNot present

The water fight segment involves spraying family friends and children, with one instance of a child crying, but this is framed as playful fun at a party rather than targeted cruelty or bullying.

See evidence (2)

“child crying during the water fight”

“'I completely destroyed them until I ran out of water'”

Dangerous Internet ChallengesA little

While the video builds an extremely high-pressure water gun (2,400 PSI), it explicitly warns in the description that this is dangerous and 'basically a bomb,' framing it as a professional engineering project rather than a challenge for viewers to replicate.

See evidence (1)

“Description warning: 'BUT SERIOUSLY 2,400 PSI IS BASICALLY A BOMB. WE TOOK A LOT OF PRECAUTIONS NOT SHOWN HERE SO ONLY ATTEMPT THIS IF YOU KNOW WHAT YOU'RE DOI[NG]'”

Low-Quality, Extreme & Stunt ContentA little

The video has some stunt-like elements (destroying watermelons, breaking glass with water pressure) but these serve as legitimate demonstrations of engineering principles rather than pure shock-value content, and the overall framing is educational.

See evidence (3)

“Watermelons being destroyed by the high-pressure water stream”

“Glass being broken by the water gun”

“Water traveling at 272 miles per hour used to cut objects”

Hidden Advertising & Sponsored ContentA little

The video mentions several collaborators and links (Bob's YouTube channel, Nathan's camera rental service, Grant Thompson's channel), but these are presented as transparent shout-outs and credits rather than undisclosed paid promotions.

See evidence (3)

“Reference to Nathan's high-speed camera rental service”

“Shout-out to Bob's YouTube channel 'I Like to Make Stuff'”

“Reference to Ken Glazebrook of NASA JPL”

Realistic Violence, Threats & WeaponsA little

The gun operates at 2,400 PSI which is noted as extremely high pressure, and the description warns it is 'basically a bomb,' but the video frames this as engineering/science content and the 'violence' shown is watermelons and glass being cut by water — no threats against people are made.

See evidence (3)

“2,400 PSI, which in hindsight is probably overkill”

“destructive power of a stream of water traveling at 272 miles per hour”

“watermelons being destroyed by the water stream”

Playful & Fantasy ViolenceSome

The video features a water fight at a family party and destruction of watermelons and glass objects, which qualifies as playful/stylized violence — the water gun is used in a fun, competitive context with family and friends, though the extreme pressure (2,400 PSI) adds a slightly more intense dimension than typical toy play.

See evidence (5)

“Water fight at a family party: 'group yelling, water splattering, group screaming'”

“Watermelons being destroyed by the water stream”

“Glass being broken by the water gun”

“'I completely destroyed them until I ran out of water'”

“Description reference: 'This could definitely shoot Ralphie's eye out' (A Christmas Story reference)”

What Parents Need to Know

Mark Rober's World's Largest Super Soaker is a creative STEM video that teaches kids real concepts like pressure, center of mass, pneumatics, and engineering design in an entertaining way. The interview with actual inventor Lonnie Johnson is a standout moment that models curiosity and professional engineering as aspirational. On the cautionary side, the gun operates at 2,400 PSI — 8 times the pressure of a fire truck hose — and is used to cut watermelons and shatter glass, which is presented as exciting rather than dangerous. A child crying briefly during the water fight is audible. The destruction sequences are playful rather than alarming, but parents of younger or more sensitive children may want to watch alongside them to provide context that this is a professional build, not something to replicate at home.

Talk to Your Kids About

1What did you learn about how a Super Soaker works, and what surprised you most about the science behind it?
2Why do you think Mark said 2,400 PSI was 'probably overkill'? What does that tell us about thinking through the consequences of our designs?
3Lonnie Johnson came up with the Super Soaker idea while doing experiments at home after work. What does that tell you about where good ideas can come from?
4If you could invent or engineer something just for fun, what would it be and how would you build it?

Protected Viewing

What's This Video About?

Introducing the Guinness World Record Largest Super Soaker evaa at 7 ft long!! This could definitely shoot Ralphie's eye out. Bob's Video- https://www.youtube.com/watch?v=gL5CO2wlBgE&feature=youtu.be Thanks to Nathan for the High Speed camera. If you need a High Speed camera to rent for super cheap check him out. Insanely low prices for great gear- http://www.aimed-research.com/ Grant Thompson from the King of Random made a version himself. Mine is WAAAY longer by an inch though: https://youtu.be/sMcVfEt6Di0 Shout out to my buddy Ken Glazebrook of NASA JPL fame for his significant help on designing and fabricating the gun. Dani does prop work and made the gun look as amazing as it does- https://www.facebook.com/GatewayProps/ More info on Super Soaker inventor Lonnie Johnson- http://johnsonstem.org/ Link to our CAD files and build lists (BUT SERIOUSLY 2,400 PSI IS BASICALLY A BOMB. WE TOOK A LOT OF PRECAUTIONS NOT SHOWN HERE SO ONLY ATTEMPT THIS IF YOU KNOW WHAT YOU'RE DOING. I DON'T WANT TO HAVE TO ATTEND YOUR FUNERAL BECAUSE I DON'T LIKE TO TRAVEL): https://www.dropbox.com/sh/yb0yshpf1sebguj/AAAiI8gpq63N7fZMJGJoNLwVa?dl=0 MUSIC- 0:27- Cereal Killa- Blue Wednesday - https://soundcloud.com/bluewednesday/ 1:02- Time to be Sad- Andrew Applepie- http://www.andrewapplepie.com/ 2:15- Berlin- Andrew Applepie- http://www.andrewapplepie.com/ 6:35- Frisbee- Andrew Applepie- http://www.andrewapplepie.com/ 8:44- Too Happy to be cool by Notebreak- https://soundcloud.com/notebreak/dubstep-too-happy-to-be-cool Summary: I made the world's largest Super Soaker as a follow up to my World's Largest Nerf Gun. It shoots at 2,400 psi and 243 mph. I destroy a bunch of stuff in slow motion and talk to the inventor of the Super Soaker Lonnie Johnson. PLEASE CONSIDER SUBSCRIBING: http://tinyurl.com/MarkRober-Sub **************************************** I make videos like this once a month all year long while supplies last: CHECK OUT MY CHANNEL: http://tinyurl.com/MarkRober-YouTube FACEBOOK: https://www.facebook.com/MarkRoberYouTube TWITTER: https://twitter.com/#!/MarkRober INSTAGRAM: https://www.instagram.com/markrober/

Frequently Asked Questions

What age is this video appropriate for?

We recommend this video for ages 8 and up. The content is largely educational and playful, but the destruction sequences — including glass shattering and watermelons being cut by a high-pressure stream — may be overstimulating or confusing for younger children without context.

Is there anything dangerous or harmful shown in the video?

The gun operates at 2,400 PSI, which is powerful enough to shatter glass and slice through fruit, and these moments are shown on screen. While no people are harmed, parents should clarify that this is a professional engineering project and not safe to attempt at home.

Is this video educational?

Yes, it has strong educational value. It explains real engineering concepts like pressure, center of mass, pneumatics, and nozzle design in accessible language, and features a genuine interview with Lonnie Johnson, the inventor of the Super Soaker, about how he developed the idea.

Is there any advertising or sponsored content in the video?

Mark briefly mentions his friend Bob's YouTube channel 'I Like to Make Stuff' and links to CAD files and a build list in the description, which are mild promotional mentions. There is no paid sponsorship disclosed in the transcript.

Is the water fight at the end safe and appropriate?

The water fight segment is lighthearted and family-oriented, involving friends and children. A child can briefly be heard crying, likely from being surprised by the water, but the overall tone is fun and no one appears to be hurt.

Does this video encourage kids to copy dangerous behavior?

The build is clearly framed as a complex engineering project requiring professional tools and expertise, which makes replication unlikely. However, parents of younger children may want to explicitly reinforce that the pressure levels used are far beyond safe DIY territory.