Free to use; extras unlock with a one-time purchase. Above 3,000 m the rule is simple and easy to lose track of: sleep no more than 500 m higher than the night before, and rest a night after every 1,000 m. Highcamp keeps the count for you. It records the altitude you sleep at each night and, during the day, shows how much higher tonight would be if you camped where you stand, and whether that keeps to the rule. Everything comes from the watch's own altimeter; no phone connection is needed. Made for the Instinct 2, 2S, 2X, 3 Solar and E (40/45 mm) and the Descent G1, where tonight's gain sits in the round window, and also on round fenix, Enduro, tactix, quatix, Forerunner, MARQ, Descent Mk2 and vivoactive watches with a memory-in-pixel screen. - Tonight: on the move, HERE and the gain over last night's camp if you slept here; in camp, NIGHT and last night's gain. OK under the daily limit, OVER (shown inverted) above it, LOW under 3,000 m. - Altitude: the current altitude. - Sleeping altitude: taken each morning as the median of the altimeter during the sleep window set in your watch profile. A night spent on the move (a summit push leaving at midnight) is marked with a question mark. Customize it in the Connect IQ app. The colours (black on white, or white on black) are free. These are marked with a star in the settings and can be used during a 7-day trial, then stay unlocked for good with a one-time purchase ($3.99) at murmurgram.gumroad.com/l/highcamp: enter the 12-character Watch face ID from the settings at checkout, and type the key you receive by email into Unlock key. - Time font: five more styles for the time besides the dot matrix: condensed, segment, stencil, outline and geometric. - The night log: the last 14 nights as bars, with the base altitude as a dotted line. - The expedition: the day of the trip above the base altitude, the average ascent per night (inverted above the daily limit) and the gain left before a rest night is due (REST DUE). - Your own thresholds: base altitude, daily limit and rest interval, if your guide or doctor uses other numbers. The screen shows CUSTOM while they differ from the defaults. - The window: tonight's gain, the average, the rest count, altitude or the latest Pulse Ox reading. The rules are the Wilderness Medical Society's guidelines for preventing acute mountain sickness. Highcamp is a counting aid, not medical advice: watch for symptoms and descend if they get worse. The face records a night only while it is on the watch, so install it before you leave; an altimeter drifts with the weather, so a night within 50 m of the last counts as a rest night. Privacy: everything is computed and kept on the watch. Nothing is sent anywhere. If you buy the unlock, Gumroad handles the payment and your email address is used only to send your key and for support. Permissions are used for the sensor history (altitude, Pulse Ox) and the user profile (your sleep window).

A starred Time font setting gives a choice of six time fonts (the dot matrix stays free).