If as your tag line suggests, you are taking quite a risk using an Apple Watch SE surfing. From Apple's own link on Water and Splash resistance of Apple Watch is the following:
"Apple Watch Series 2 and later can be used for shallow-water activities like swimming in a pool or ocean, but you shouldn't use models other than Apple Watch Ultra for diving, water skiing, or other activities involving submersion below shallow depth or high-velocity water."
Surfing is most assuredly exposing your watch to high-velocity water and should it become damaged from this activity, it won't be covered under warranty at all.
I would highly recommend you consider getting the Apple Watch Ultra, which is the ONLY Apple Watch which is purpose built for such activities as this. And you can choose the Ocean Band with the Ultra, which would be ideal for what you need.