Technically yes and it's advertised to be able to use with swimming. HOWEVER if you call for warranty support the first thing they ask before accepting your watch is if you got the watch wet or wear it while showering. There's a test strip inside that changes color if it gets wet and voids the warranty. It's "suggested" in the instructions you don't get it wet even though they advertise it as water proof to a certain depth.
You're out of luck if you don't have any other usb c adapters. $300 watch and no usb c charger? Thanks Samsung.
Yes but not continuous. You have to wear the watch on the left and manually tell it to take a 30 second recording while keeping your right index finger on the top button. It only checks for AFib. It does NOT automatically record or check or alert you to any abnormalities while wearing it during normal wear. Also if you set up the ECG then the health app forces you to set up a screen lock on your phone.
You can use Google maps on the watch. If your hike is on a path that is visible to Google maps you can retrace your steps. There might be a third party hiking app that allows this as well. For all these features you need to be within Bluetooth range of your phone and have a signal (or LTE phone with a line and signal).