There is only one watch with an audible alarm, the citizen aqualand duplex. Not only is the alarm loud, but you can program the number of beeps: 1, 2, 3, 4, 5.
So, you could wear 5 citizen aqualand duplex watches, and have one of them beep once at 10m, another beeps twice at 20m, and so on.
It measures digital depth to .1m down to 80m, but the digital display is small. It records 4 dives but it is scuba style, so you would need to reset it after each freedive if you want to record individual dives. It malfunctions in water 6C or less, like all citizen and casio watches. Only the suunto watches work in icewater.
Size-wise, it is tiny, much smaller than a suunto watch or apneist.
Eric Fattah
BC, Canada