Here is a good 60 minute social-distanced-holiday-swim-challenge.
50s
choice x 60 minutes with fly overs. Start with a person in each lane at both ends of the pool. One side of the pool pushes off and as they get to the backstroke flags the second swimmer streamlines underneath them.
The second group swims a 50. When that swimmer reaches the backstroke flags the first group pushes off underneath them for their 50 choice. Alternate 50s for the rest of the hour. Merry Christmas!!