I just realized, in the same sense that an ultramarathon is longer than a regular marathon, extremely large/big solves could be considered ultracubing.
Some big stuff:
- 121x121x121 by Adrian Acosta, and I'm going to try a 128x128x128 sometime soon
- 30x30x30 with keyboard by me
- Yottaminx by me
- 55x55 sliding puzzle by soup
- 95/100 multiBLD by Marcin Kowalczyk
- 7x7x7x7x7 by Matthew Sheerin and separately by Ethan Muldoon
- 120-cell Mirror-Z by Andrey Astrelin (427287 moves) and Nan Ma (357330 moves)