Getting Faster: 500s in the Pool

My oldest swim workouts that I started to do maybe around 2009 or 2010 when I got good enough to do something other than "just go for a swim" at the pool are 10-20x100s and 3x500. I've done the 3x500 workout 3 times since hopping back into the pool in September. And even with just 1 swim/week, I'm making progress.

The first time I did these, my watch and Garmin had just died, so I had to watch the clock on the wall and remember my times. Here's what I swam for those 500s:

Sept 21, 2021

8:04
7:59
7:51

7:58 / 500 average, or 1:35.6 / 100 average

Then I went back about a month later (with a working watch for splits) and swam this:

Oct 26, 2021

1:36, 1:38, 1:37, 1:36, 1:35 = 8:04.4
1:33, 1:35, 1:36, 1:34, 1:32 = 7:53.2
1:34, 1:36, 1:34, 1:32, 1:30 = 7:48.4

7:55.33 / 500 average, or 1:35.07 / 100 average

So a BIT faster, but pretty much the same sort of swim.

Yesterday, I went back for that same workout thinking I'd MAYBE do it a bit easier because it had only been 3 day since the Moustache Run Half Marathon and I didn't want to kill my legs. But I found myself swimming pretty hard and putting down even better splits. This time, I kept them all under 8:00 (with only 2 of the 15 splits being at 8:00 pace [which is 1:36/100]):

Nov 30, 2021

1:33, 1:35, 1:34, 1:35, 1:33 = 7:52.66
1:32, 1:36, 1:35, 1:33, 1:31 = 7:48.98
1:30, 1:35, 1:36, 1:33, 1:30 = 7:46.19

7:49.28 / 500 average, or 1:33.86 / 100 average

At my peak in the pool (maybe 2015-ish?), I could keep them all around 7:30 with my last 1 sometimes ducking into the "teens" at 7:1x, so I still have a ways to go, and I don't plan on getting there with just 1 swim/week. But I *AM* really enjoying a nice swim each week, and I think I'll miss it in the spring when I don't have pool access anymore.