Most surf watches stop after telling you when the tide is coming in. The new G-Shock G-LIDE GBX-H5600KI-5 also checks your heart, studies your sleep and expects you to catch the next wave.

Casio has released its fourth signature watch with Japanese professional surfer Kanoa Igarashi. The GBX-H5600KI-5 is based on the heart-rate-equipped G-LIDE GBX-H5600, but its brown marbled body and soft purple details give it a look that is easy to separate from the standard models.

A colour scheme inspired by Portugal

The mixed brown colour is inspired by the cliffs and rocky coast around Ericeira, Portugal, one of Igarashi’s training bases. Casio mixes different colours of bio-based resin during production, so the streaks and marks will not be identical on every watch. That gives each example a slightly different surface pattern without pretending that the watch is hand-finished.

The lavender details are a smart contrast to the dark case. A purple vapor-deposited finish around the display is meant to recall the sea during the early morning and evening magic hours. Igarashi’s signature sits below the screen and also appears on the back. His World Surf League competition number, 50, is printed on the lower part of the band.

Built for the water, but useful away from it

The case measures 51.1mm long, 44.5mm wide and 17.3mm thick. That is a large watch on paper, although 47 grams is impressively light for a G-Shock with an optical heart-rate sensor. The carbon-fibre-reinforced resin back helps keep the weight down. The bio-based resin band fits wrists from 145mm to 215mm, while shock resistance and 200 metres of water resistance make the watch suitable for serious time in the sea.

The Memory in Pixel LCD is clear and can show a large tide graph directly on the watch. There are 50 preset tide locations, with around 3,300 points available through the Casio Watches app. Moon data, sunrise and sunset times are also included. The glass is mineral rather than sapphire, which is common for this type of G-Shock but worth knowing before buying.

Heart rate, training and sleep data

An optical sensor measures heart rate from 30 to 220 beats per minute. The watch also has an accelerometer for steps, distance, speed and pace. Running, walking and multi-sport modes support automatic or manual laps plus auto pause. Up to 100 runs can be stored, with as many as 200 lap records for each activity.

Casio uses Polar algorithms to turn that information into training, recovery and sleep analysis. Sleep score, breathing exercises and blood oxygen readings are part of the package, although the blood oxygen function is not a medical device. Four daily alarms, a smart alarm with vibration, a 60-minute timer and a stopwatch that runs up to 99 hours, 59 minutes and 59 seconds cover the normal digital-watch jobs.

Bluetooth links the GBX-H5600KI-5 to the Casio Watches app. The connection provides automatic time correction, about 300 world-time cities, phone notifications, activity logs, sleep records, phone finder and smartphone GPS correction for more accurate distance measurements.

Solar assistance with USB charging

This is not a conventional Tough Solar model that can run every feature indefinitely from room light. The main battery is charged with the supplied USB cable, while solar power helps extend the time between charges. Casio quotes about 35 hours when the heart-rate sensor is used continuously for activity tracking, around one month in normal watch mode with heart rate turned off and up to 11 months with power saving enabled.

Other practical details include a full-auto white LED backlight, 38 watch-based world-time cities plus UTC, a full automatic calendar through 2099, 12 or 24-hour display and airplane mode. Accuracy is rated at plus or minus 15 seconds per month when the watch is not connected to a phone.

Price and availability

The G-Shock G-LIDE GBX-H5600KI-5 was announced on 21 July 2026 and reached stores in Singapore on 31 July. Official prices include SGD499 in Singapore and ¥50,600 in Japan. Based on current exchange rates, the Singapore price is approximately $387, €340 or £290. These are conversions rather than confirmed prices for the United States, the euro zone or the United Kingdom.

Conclusion

I like that Casio did more than change the colours for this collaboration. The marbled resin connects directly to Igarashi’s time in Portugal, while the purple accents stop the brown case from looking dull. More importantly, the tide data, heart-rate sensor, sleep tracking and light 47-gram construction make sense for an athlete who spends much of his life in the water. It is a focused G-LIDE with a strong design, not just a name printed on the box.