| Event | Time | Meet | Date |
|---|---|---|---|
| 100m Backstroke | 1:19.73 | Western Transmountain Festival I | 2026-02-14 |
| 100m Backstroke | 1:17.14 | Cascade Speed Meet 2025 Provincial Series #1 | 2025-11-08 |
| 100m Breaststroke | 1:27.82 | Western Transmountain Festival I | 2026-02-14 |
| 100m Breaststroke | 1:22.00 | Winter Provincial Trials | 2026-03-06 |
| 100m Butterfly | 1:18.52 | Western Transmountain Festival I | 2026-02-14 |
| 100m Butterfly | 1:19.84 | Winter Provincial Trials | 2026-03-06 |
| 100m Freestyle | 1:09.19 | Western Transmountain Festival I | 2026-02-14 |
| 100m Freestyle | 1:06.64 | Pugsley's Plunge 2026 | 2026-01-16 |
| 100m IM | 1:15.90 | Winter Festival | 2026-01-23 |
| 200m Backstroke | 2:52.49 | Summer Provincial Trials LC | 2025-06-27 |
| 200m Backstroke | 2:42.26 | Nose Creek Invitational 2026 | 2026-03-14 |
| 200m Breaststroke | 3:09.92 | Summer Provincial Trials LC | 2025-06-27 |
| 200m Breaststroke | 2:59.55 | Winter Provincial Trials | 2026-03-06 |
| 200m Butterfly | 3:02.52 | Nose Creek Invitational 2026 | 2026-03-14 |
| 200m Freestyle | 2:27.19 | Western Transmountain Festival II | 2026-02-17 |
| 200m IM | 2:53.03 | Western Transmountain Festival III | 2026-02-20 |
| 200m IM | 2:38.50 | Winter Provincial Trials | 2026-03-06 |
| 400m Freestyle | 5:12.50 | Nose Creek Invitational 2026 | 2026-03-14 |
| 400m IM | 6:02.31 | Sandy Ferris Age Group Food Bank Challenge 2025 | 2025-12-19 |
| 50m Backstroke | 37.30 | Western Transmountain Festival III | 2026-02-20 |
| 50m Backstroke | 35.19 | Winter Festival | 2026-01-23 |
| 50m Breaststroke | 39.31 | Western Transmountain Festival I | 2026-02-14 |
| 50m Breaststroke | 37.20 | Winter Provincial Trials | 2026-03-06 |
| 50m Butterfly | 34.72 | Western Transmountain Festival III | 2026-02-20 |
| 50m Butterfly | 34.36 | Western Transmountain Festival II | 2026-02-17 |
| 50m Freestyle | 30.27 | Western Transmountain Festival I | 2026-02-14 |
| 50m Freestyle | 29.54 | Winter Provincial Trials | 2026-03-06 |
| 800m Freestyle | 11:20.21 | 4th Annual Comet Cup | 2025-11-14 |
Thiessen, Matthias's top personal bests include 100m Backstroke (1:19.73), 100m Backstroke (1:17.14), 100m Breaststroke (1:27.82), 100m Breaststroke (1:22.00), 100m Butterfly (1:18.52).
Thiessen, Matthias swims for Cascade Swim Club.
Thiessen, Matthias has competed in 14 meets.