For the major part of Mandela’s stay on Robben Island, his cell, like all others, had no bed or mattress, just two mats. What appears to be a pillow are 5 blankets, which he had to keep like this when he was not asleep.
The mats provided were the best you could get. Note the South African Bureau of Standards stamp of approval (SABS).

There have been many requests to stay overnight in this all purpose room in the last 15 years. It served as bedoom, living room, bathroom and toilet, dining room and recreational space for one man for 18 years, though it is just 2 metres square (that’s 6ft 6in sq.).
This is where Nelson Mandela spent most of his time at Robben Island, sleeping, washing, eating, exercising and thinking. He is 6 ft 2in and couldn’t lie down without bent knees. The electric bulb burnt all night. He was taken out of the cell each day pre-dawn to join the other prisoners to break stones or make roads and returned to the lock up at 4 pm.
There are about a dozen cells on each side of this corridor in Block B, all principally the same. It’s where the most important political prisoners were kept.
Far from being in solitary, they were caged alongside each other. With care and discretion, they could communicate.
The idea was that they would do less damage if they were isolated from the rank and file political prisoners.
The diet was meagre and the beverages restricted to tea, coffee or water.
When Mandela was released, at the age of 72, he had never tasted dry wine. Within weeks, he was honoured and feted, virtually every day, and as a rule, next to his plate, he found the juice of the grape, fermented dry, red or white. He was not impressed.
He remains, today, the world’s most famous sweet wine lover.