XDEEP  recently released an upgradable bottom timer that has seen so much interest that supply hasn’t kept up with demand, which means it took a bit longer for me to acquire one for this review.

I’ll be reviewing the Black BT, which is the basic version. The BT in the name stands for “bottom timer,” which means the unit differs from a dive computer in that it won’t calculate your no-decompression limit (NDL), along with a few other bells and whistles that a computer offers. Essentially a bottom timer’s basic function is to give you depth and dive runtime. But the XDEEP gives you a bit more than that and can be upgraded to either a multi-gas nitrox dive computer (BLACK EANx) or trimix dive computer (BLACK TMX) depending on budget and needs.

Tech specs

Tech specs are on the company’s website, but some notable features include a 1.8” OLED display, an 8 MB flash memory and a depth rating to 656 feet (200m). The XDEEP Black BT also has a whole host of functions that go beyond just simple depth and runtime measurement, including:

  • Customizable and in-dive configurable alarms for maximum depth, average depth, total dive time, alarm clock and battery level
  • A stopwatch with reset, pause and resume functions
  • Compass with waypoint guide function
  • Dive profile
  • Log book that supports UDDF
  • Ascent/descent speed indicator bar graph with digital speed value, which can be set for optimal/maximum speed for different depth ranges
  • Multiple color schemes, plus user can define his own
  • Screen-flip sensor is customizable
  • Brightness and dimming is customizable
  • Information displayed on three main screens (home screen, dive profile and compass), which are navigable with single clicks
  • Easy-to-use navigation and settings functions

First impressions out of the box are that it’s much smaller than I had expected and pretty solid. As I would be diving in a drysuit, using the bungee option made more sense than using the supplied strap, which you can still use even with the bungees in place. Obviously since it was a new toy I only gave it a quick charge so I could start playing immediately. If, like me, you never really read manuals, then you will find the XDEEP Black BT is pretty straightforward to operate. The unit starts up when you click both buttons a couple of times. Accessing the menus is a simple long press to confirm and a short press to navigate through the options. The settings menu is straightforward and allows you to customize many aspects of the unit. After changing the screen color a few times to check out the options, I decided to leave the rest at factory settings. There is even a demo option that simulates a dive if you wish to check the dive screens before you get in the water, handy to help familiarize yourself with the information screens. The unit charges with a USB and takes around 1.5 hours for a full charge, which then provides around 20 to 40 hours of runtime. My 40-minute test dive with lots of use resulted in a 3 percent drop in charge in relatively warm water.

In The Water

The first thing you notice underwater is that the reflective screen suffers from glare in bright conditions, much like a mobile phone. As you get deeper and surface light dims, this is no longer an issue. The next thing that struck me was how easy the buttons were to operate. I was wearing 7mm gloves and found it easy to press each button.

One thing that I found mildly annoying on dry land was the sensitivity of the screen flip — again, most smartphone users will know how annoying it is when the screen flips when you don’t want it to or when you want it to and it doesn’t (#firstworldproblems). Once underwater, though, it was not a problem. When you’re in trim, your arms don’t move around enough for it to be an issue, and if you want to show your screen to your buddy, you just stretch out your arm and angle it towards him so he can read it without either of you having to contort yourselves, as with a fixed-screen computer or bottom timer. This feature is particularly useful during deco stops. The Black BT’s settings also allow you to change the sensitivity of this sensor.


The display on this unit is phenomenal; the vis on the test dive was pretty poor in places, but as you can see in the photos the screen is very easy to read even from a distance. The screen image is clear and the information is easy to take in at a glance. Having played with the predefined color themes, I found that the standard one was the best in all light and vis conditions. It’s easy to swap themes and brightness during a dive, so you can adapt as your dive goes along. During a dive there are three main information screens that can be navigated via a simple click of the buttons: left to go left or right to go right — simple.

Screen one is the dashboard screen with all your main dive information — current depth, average depth, max depth, dive time, battery life and ascent/descent speed. This screen can be customized with three settings for full information, simple or basic. The ascent/descent speed indicator, or VSI, provides you with at-a-glance buoyancy control. It displays current ascent or descent rates in meters per minute and through a color bar graph red = bad/green = good. If neither is displayed then you’re in neutral buoyancy. This is particularly useful for deco stops, especially in an environment where you have no other reference points.

Screen two is the compass screen, which features a clear and easy-to-use compass while also displaying depth, dive time and ascent/descent speed. Unfortunately I didn’t get a chance to test the navigation-by-waypoints function on the test dive. According to XDEEP, this function allows you to upload a text file to the unit containing the course in degrees and time spent covering distance in seconds. Once in the water, as soon as you select the compass screen, it will automatically start guiding you along this route.

Screen three displays your dive profile with current run time and temperature. Out of the water the home screen displays time, date, temperature, battery life and surface time.

Post Dive

Out of the water, there’s a logbook function that can hold between 300 and 2,000 hours diving, depending on the settings. This logbook function has a number of screens, which basically aggregate the information from the dive screens across a whole dive (excluding the compass) and includes a dive-profile graph and a temperature graph.

A big thanks to Robert Lange of Lange Tauchen and DIR Tec Shop for supplying the hard-to-get unit. If you’re in one of your own, drop him a line while he has some in stock. More information can be found on the XDEEP website.


9ScubaDiverLife score


  • Easy to use
  • Updateable
  • Clear, bright screen
  • Customizable
  • Comes with USB charger
  • Screen suffers glare in bright conditions
  • Recreational divers will still need a computer

The XDEEP Black BT is a simple and easy-to-use bottom timer, which offers a number of additional functions over a standard BT, and it’s easy to upgrade to a full Nitrox or Trimix computer via Firmware.

Black BT: $429
EANx computer: $629
Trimix computer: $799