USPRT Workouts?

Well if you're aiming for a 15k swim, you need to get used to boring. Going those distances is as much about the mental as it is the physical part of it. As I've said before, you need to get your body and mind trained for those hours in the pool to prep you for OW. You need to do the work in the pool to get consistency and pacing down in order to be successful in OW. Go dig into training that the competitive OW swimmers are doing and I guarantee there are a lot who train mostly in the pool. If you can't hang, you need to just go back to orienteering. And to continue the insight that many of the others have given, I started swimming Master's about 6 years ago. Entered my first OW race a year later just to see what i could do. Each race, I learned something new to make the next one better and more efficient. I've had several coaches and each one has given a different perspective and that's training with them 3-5x per week all year around. I work on my stroke ALL THE TIME; constantly checking in on form, technique and efficiency. And it's 6 years of gradual improvements for me to finish competitively in many of the races I'm in. As others have said, swimming has a ton of nuance and you have to make tweaks over time. If you're unwilling to put in the time or listen to what people have been telling you for three pages of forum, then I just don't know what to tell you. Maybe Orienteering is your sport.

Well if you're aiming for a 15k swim, you need to get used to boring. Going those distances is as much about the mental as it is the physical part of it. As I've said before, you need to get your body and mind trained for those hours in the pool to prep you for OW. You need to do the work in the pool to get consistency and pacing down in order to be successful in OW. Go dig into training that the competitive OW swimmers are doing and I guarantee there are a lot who train mostly in the pool. If you can't hang, you need to just go back to orienteering. And to continue the insight that many of the others have given, I started swimming Master's about 6 years ago. Entered my first OW race a year later just to see what i could do. Each race, I learned something new to make the next one better and more efficient. I've had several coaches and each one has given a different perspective and that's training with them 3-5x per week all year around. I work on my stroke ALL THE TIME; constantly checking in on form, technique and efficiency. And it's 6 years of gradual improvements for me to finish competitively in many of the races I'm in. As others have said, swimming has a ton of nuance and you have to make tweaks over time. If you're unwilling to put in the time or listen to what people have been telling you for three pages of forum, then I just don't know what to tell you. Maybe Orienteering is your sport.