Pencil dilemma

[lowwall]

Look at a mechanical pencil, aka "lead holder" in larger diameter sizes. You can see all the lead options along with some recommended pencils/holders here: Mechanical Pencil Lead Size Comparison | JetPens

The Pilot Croquis linked above from Piranha and Amazon is also their recommendation for 4mm leads.

 

[Martijn]

AQUA PENCIL STARTER KITS I love this one

 

[rhwestfall]

For $2 I don't have an aversion to these: Underwater Writing Tool w/Cap and Bungee

 

[maj2]

In addition to a few of the choices listed above, I have also used a plastic carpenter's pencil with a retractable lead. It's size is handy when wearing gloves in cold water.
Something like this:

https://www.grainger.ca/en/product/p/JHL40-0665

 

[Bratface]

Aqua Pencil is the best and lasts a long time. Refillable lead. I’ve used one for about 14 years. My backup pencil is one of those flat carpenter pencils. Cut it to the length you like. Drill a hole in the end and tie a piece of string or cord through the hole. Tie the other end to your slate. The lead doesn’t fall out of them as easily as a regular pencil.

 

[fisheater]

I've found Croquis(es) to be very reliable underwater. You can even put some thin bungee through the top and knot it off. Makes it very secure.

 

[Alastor]

I use, for every kind of pencil, a piece of heat shrink tube where I put a string, a bungee or whatever with a small knot at the end.
It is very effective, do not slip away and very cheap.

 

[Alex Ouroboros]

You won't find anything nicer.

Just trawling these posts and am so glad you had this link, couldn’t remember what they were called!! Thanks so much

 

[Marie13]

Just trawling these posts and am so glad you had this link, couldn’t remember what they were called!! Thanks so much

These are no longer made.

 

[Bigbella]

We typically used "grease pencils" or so-called "China Markers" years ago, attached by some cheap-o surgical tubing to plastic clip boards or even scrap polymer sheet from a local plastics place -- just a few bucks, tops.

Provided that the pencils were allowed to dry, they also lasted quite a while; and none of us really wanted that "grab your ankles" dive shop experience . . .