Cave Diving, Cave Exploration and Cave Mapping in Yucatan, Mexico
Cains Australia and the local staples.

My Cave Diving Side-Mount Helmet

March 2009:  I have updated the design of my helmet.  You can read about my new cave diving helmet here.

When I was doing research/preparing for my side-mount course, I was tasked with getting a helmet. If you are not a diver, not a back mount diver or an open water diver, you might be asking yourself, “Why do I need a helmet under water?” There are a couple of reasons:

  • You need some place to mount your lights to keep your hands free while laying line, surveying or giving Patrick the finger. It is infinitely cooler to clip your light to your helmet, then to put it over your neck.Sidemount Helmet with HID
  • You should protect your head if you are going to be in a very small passage. The top of my helmet is scratched.
  • You should protect your head if you are using a DPV. I image you could knock yourself silly on an N19 in the cave.
  • It looks unbelievably cool and chicks dig it. When the girls see me put my purple helmet with the yellow lights, I know they are getting hot for me.
  • It gives you something to stress about before you start class.
  • It gives your friends something to make fun of you about. Maybe it will distract them from noticing how awesome a diver you are.
  • Lastly, mounting and dismounting your light will make the rest of the team nuts with confusing light signals. (Sorry Katie)

Since I had no idea what I was looking for in a sidemount helmet, I turned to the internet. Unfortunately, my search skills failed me and I found limited information on helmets for cave diving. I did find some excellent photos from a site in the UK. But they seemed to focus on sump divers.

After suffering a tolerable level of frustration, I started to page my friends here in playa. Patrick and Fernado, of Protec fame, answered the call and let me take a look at their helmets. Patrick’s helmet is a modified construction helmet. It is red and has two SL4s and a mount for his HID. The helmet is secured by a plastic clip and a basket inside the helmet. I think Patrick’s helmet is 3rd generation. I know he has spent a lot of time working on it and it has cost him.

After a review of his helmet and finding out I could get myself a helmet like his at the electrical store on Ave Jaurez, Patrick instructed me to go to Walmart or Mega and get a kids helmet. Not a foam one, just a plastic one with a liner. I think Patrick’s helmet was about $25USD.Sidemount Helmet Side SL4

I checked Walmart here in Playa del Carmen and NO helmets. Lots of bikes but no helmets. I found that weird. Then I went two blocks to Mega and I found the perfect helmet. It is purple, fits about right and it cost $55 pesos. Yes, it cost about $5USD. I thought, “This is awesome! If I am going to trash something by drilling holes in it and modifying it, at least it isn’t an $80USD kayak helmet.” Steve Bogaerts and some of the other elites use Kayak helmets.

I got the helmet home and started the experiment. I had read that you want to put the lights at eye level. I don’t remember why. So I decided to mount the HID on the right side where the SL4 is now. I put an SL4 apposing the HID mount and above the HID mount. The photos should make it clear what I mean, you will have to imagine a little. (All images are clickable and lead to a larger photo. I think you should click one!) All the lights are mounted with zip ties.

Originally, I tried to mount the HID using the plastic bracket that came with the goodman handle. This piece proved to be too brittle and broke while I was trying to mount it. A quick phone call and Patrick hooked me up with a piece of usedSidemount Helmet Front View PVC pipe. Believe it or not, he found it a couple of hundred feet back in Minotauro. He is using the same worn pipe for his helmet. The only difference is I am using 1 layer, my light head is bigger, and he is using two layers of the pipe nested.

I aimed the lights so that they all focused in the middle about 15 feet away. It seemed logical to me. There was 3 pieces of foam in the helmet. I removed the two side pieces and left the top piece which runs the length of the helmet inside. The helmet was a little narrow and a little long with the foam. Now without it, the width is about right maybe a little wide and the length is unchanged.

Steve Bogaerts said that the final test is to take it diving. Everything has to go in the water to be proved. So I took it diving and it was clearly a first attempt. Here were the immediate problems:

  • The HID was in such a position that it cast a weird light in my eye. I really hated it below the SL4 and inline with my eyes.
  • The HID was aimed way too close. To be honest, in the first 5-10 feet I only need the edge of the cone of light. I don’t need the hot spot right there.
  • The helmet was too low in the back. When my neck was up the helmet was resting on the hoses and was being pushed down into my mask. This was uncomfortable and made removing tanks a bitch.
  • The HID is on the WRONG side. I would have never know this if I didn’t practice doffing and donning bottles in the water. The right bottle is last on and first off in my world. If the light is on that side, it is always in the way. You have to remove it from the helmet to remove the reg, if you clip it on the right D ring, then it is in the way when you deal with the buggies and it gets all caught up. Putting on the bottle is just as painful with the light there.

Sidemount Helmet Side HIDSo, I had some changes to make. I moved the HID mount to the left side and I changed my cable routing to the left side. I wear my HID butt mounted. I put the two SL4s in parallel on the helmet and left the aiming about the same. I moved the HID to above the left SL4 and I aimed it up a couple of degrees. This way I don’t have to arch my head so far back to get a little bit of reach out of the light in big cave. The cone of light is just right now. It is also out of my eyes. Lastly, I trimmed the rear bottom edge of the helmet to give me some room. Unfortunately, I have limited tools here, so I was restricted to a utility knife, hacksaw and sandpaper. I did the best I could, but it is still not right. I will take another wack at it later.Sidemount Helmet Front View

The helmet is a little loose on my head and the foam inside is less then optimal. The helmet is negative, however the foam soaks up water and has noticeable inertia when I move my head. I am sure some of it is the three lights, but I think some of it is the water trapped in the foam. Also, Steve says the foam is raising my profile too much. One of these days I will work on it some more. Maybe it is an excuse to buy a Dremel.

So that is the story behind my helmet. As it evolves, I will keep you informed. If you have any questions about helmets, send them in and I will find the proper person to answer them.


1 Oliver { 03.27.09 at 2:50 pm }

Hi, that’s funny I ran into your stuff. I might be getting one of those cheap cheap home made video housing and need to hole my lights on my head… I guess I’ll be investigating wall mart soon too. The whole challenge is to do “fine art video under water with cheap minimalist equipment, just like pinhole cameras in the old days… to be continued !

2 Hans { 03.27.09 at 3:02 pm }

Oliver! Glad you found me. When you get your helmet together, send me some photos. I will be interested to see them….

BTW, I had an awesome time diving with you and Andrew. You did a great job.


3 Ed Leme { 01.06.10 at 1:51 pm }

After having looked for a helmet that I could utilize during my solo diving in south Brazil, I ran into your nice article. Your words gave me many ideas about how I could put together this important safety apparatus. I am a solo diver, and what made me think about wearing a helmet was having seen a 4 kg weight hit the air tank of another diver. The weight was accidentally dropped by another diver while he was trying to become more negative at the surface by adding the piece to his side-pocket! The bombarded diver was approximately 20 meters down; the impact made him became closer do God. In any way, since I do not do cave diving, but do dive alone in Brazil, I thought that I make this equipment a part of my safety gear, mainly after reading about the advantages! I think that I will try the Kayak Helmet to start! Thanks! Visit my blog, would you?
Ed from Brazil

4 Hans Kaspersetz { 01.06.10 at 6:56 pm }

Ed, thanks for leaving your comment. I love my helmet. I use it in both open water and in the caves. My favorite part is that it is a great place to mount my lights! This leaves my hands free for operating my rebreather or my scuba gear.

Good luck with you diving and I hope you are fully redundant. Solo diving definitely more dangerous then team diving.


5 Ken Winter { 01.18.10 at 5:52 am }

Hi Hans. I enjoy keeping up with your exploits. I have had some of the same questions you did, but I just haven’t done anything about it. How about asking some of those more experienced guys there what the real differences are between using a bike helmet, hockey helmet or kayak helmet? I haven’t had much luck with the bike helmet getting things stable. I haven’t tried a hockey helmet yet, but it doesn’t look like an improvement. Kayak helmet is about $45 and I want to know what advantages it has (other than the fact the brand name on it is Pro-Tec!)

Come on up and dive with us sometime. Bottom temp was 38 this past weekend.


6 Hans Kaspersetz { 01.20.10 at 10:01 am }

Ken, good to hear from you! I am living in New Jersey again. My wife and I had our first son back in October. He is a bundle of joy, however he has seriously curtailed my diving for now. Plus, the idea of cold water diving after living in MX is just not that attractive to me.

A word of advice on the helmet issue. Both Patrick’s and my helmets required A LOT of tinkering. Patrick uses a construction helmet and I use a bike helmet. We both removed all the internal linings and fixtures. The helmet rests directly against our hoods. We also cut the helmets so they were much smaller then the original versions. The trick is to make them very close fitting to the hood. There is no space between the helmet and my hood.

Check this blog post out, it details how I modified the cave diving helmet to fit better.

Good luck, the winter is a good time to work on stuff like helmets. Don’t be afraid to butcher it in an effort to get the right fit. Diving is not a beauty contest.


7 Alejandro { 09.06.10 at 1:50 pm }

Hey Hans,

thanks for your tips, I was interested in a helmet since I´m a wrecks and Cave diver and I´ve hit my head quite a few times. nothing bad but it hurts a lot. I have only one question, I have a couple of DIR diver friends that gave me a comment when I told them about the idea of buying a helmet and they told me the problem with a helmet is that you could blind your buddy when you look at him. Any advice or comments on that?

best regards,


8 Richard { 06.11.13 at 10:34 am }

hello Hans, i used a hard hat and took the liner out of it. I glued window insolation around the edge and two running back to front. I cut out the front to go around my mask. mounted lights to both sides. Works good and i was cheap. Found the hard hat on the edge of the highway.
be safe