No reason to swim - it doesnt offer you nay protection and is just awkward and weird.  Everyone knows who you are talking about and SWIM is basically only associated with recreational drug use.  This forum encourages posters to skip on the SWIMing.....

San Pedro is very easy to extract.  Totally safe.  I have drank it a few hundred times.  I know shamans in Peru who have been drinking it for 40+ years. 

Easiest way to make it - chop it up small and boil everything except for the hard woody core for about 5 hours.  If you like add a lemon or lime to the pot before boiling.  Then strain out and either drink it as is, or reduce it.  Easy peasy.  (I have brewed this a couple hundred times)

People that dont use the whole cactus miss out.  The core isnt needed and is too hard to chop anyways....  But use the rest.