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Achievements
Blue Trails hands out badges for the diving you do. They're on the Achievements tab of your profile.

Badges you've earned are in colour; the ones still ahead are greyed out, which is the point — you can see what's next.
They come in families. Dives counts how many you've logged (First Breath, Ten Deep, Century Diver, Five Hundred Club, Thousand Club), while others track time underwater, how regularly you dive through the month and across the year, and so on.
Tap any badge — earned or not — to see exactly what it takes to get it.
Badges only know what you log
A badge counts dives in your logbook. Dives you did but never logged don't count, and neither do dives sitting in your dive computer waiting to be imported.