Swimiquette...

Started swimming this week. A gym has opened up in the new hotel next to work so thought I'd join up as they have a 21 metre (68.8 feet) swimming pool.
It was fabulous Monday through Thursday as I had the entire pool to myself! Ahh, bliss. Then came Friday... there were three other people in the pool when I dived in and then all of a sudden there were seven! What on earth does one do etiquette wise? As I can only manage breaststroke I'm not as fast as the freestyle folk and as such get passed with water splashing all over me (sure they're trying to drown me!)... so do I move out the way, do they, what's up with the splashing, does everyone do the same swimming stroke or do I just manhandle several people out the pool and tell them to go away as this is my swimming time and what the heck do they think they're doing in my swimming pool?