I swam 2 km tonight. According to my watch I was slower than last night, but overall swam twice as much and rested less.
About an hour before swimming my blood sugar was 11.7 (211) so I took a 50% correction bolus. Right before swimming I was 9.5 (171). Swimming took me about an hour, and near the very end I started feeling low. I don't usually feel lows when I exercise until I am really low, and sure enough I tested at 2.2 (40). I ate three glucose tablets. I didn't want to try doing a bolus when I was that low, so didn't.
I messed up on timing the bus schedule so had to wait half an hour for the bus. An hour after swimming I was 4.4 (79) and bolused for dinner. No idea what I'll be after dinner, really. I'm glad I didn't take any bolus after swimming!