Dive watches come in all shapes and sizes, and are available at all different price points. Most watches with a uni-directional rotating bezel and the ability to fit over a wetsuit claim more water resistance then most of us will ever need: usually around 100-200 meters.

The watches I cover in this article go way deeper than your typical diver; deeper than the current 1,220 meter Rolex Sea Dweller; deeper, even, than the Breitling Steelfish which maxes out at a comparably casual 2,000 meters. There are a handful of watches out there that can literally scrape the bottom of the deepest known parts of the ocean, and I call these watches “extreme divers”.

Sapphire crystal. The Scubamaster’s crystal is highly scratch-resistant synthetic sapphire which is set down below the bezel for extra protection.

24-hour hand. The Scubamaster has four hands: hour, minute, second, and a 24-hour hand. The watch is designed to be able to easily track the time in two different time zones, and to be able to switch time zones quickly and easily. When in you home time zone, you keep the hour hand and the 24-hour hand in sync. When you travel outside your home time zone, the movement is designed in such a way that you can easily adjust the hour hand forward or backward, depending on whether you are traveling east or west. That way, the hour hand indicates the time where you currently are while the 24-hour hand retains your home time.

If you want a watch that you can see at anytime during the night, or if you work for long periods of time in a darkened environment, or if want a watch that you can use for night diving, you probably want tritium. I’m an amateur diver, so I don’t need hardcore equipment, but I really like being able to wake up at any time during the night and easily read the time. It’s worth noting that the MTM Black Seal actually uses a combination of tritium and some sort of luminescent material, as well. The tritium tubes are used for the indices and hour and minute hands, and the luminescent material is used for the numbers which means initially, you can see everything in the dark, but over time, only the indices and hands are visible (which is really all you need).

The MTM Black Seal is a big watch. With a 44 mm case and weighing in at 7.5 oz (about 2.5 ounces heavier than the bulky Rolex Sea-Dweller), it’s a serious piece of equipment. That said, I have relatively narrow wrists, and somehow, I’ve been able to get away with wearing the Black Seal. The shape of the case and lugs bends nicely along the curve of my wrist which allows it to sit very comfortably in place, wearing much lighter than it actually is. And of course the Velcro strap reduces the weight considerably, as well.

Power reserve indicator. The button on the right side of the case above the crown activates a power reserve indicator (which can actually be activated underwater). The watch’s second hand moves ahead to indicate how long the watch will remain operational, then stops there and waits for time to catch up before moving again. As long as I remember to wear the watch a day or two every couple of weeks, power is never an issue.

And then there’s the crown. The crown is big and textured to make it easy to grasp, and the threading of the crown and stem is precise which makes it very easy to release and reseal. This may seem like a given, but I’ve handled enough watches with difficult to manage screwdown crowns that I really appreciate when it’s done right.