A candle is placed next to an inscribed memorial stone, where the ashes of the late Archbishop Emeritus Desmond Tutu are laid to rest, at the St George's Cathedral in Cape Town, South Africa. [Reuters]

Anti-apartheid hero Desmond Tutu's choice of aquamation over cremation or traditional burial came as a surprise to some South Africans, while others were impressed by this environmentally conscious move.

By opting for aquamation Tutu, who died on Dec. 26 aged 90, joined a growing "green burial" movement centred around the use of biodegradable materials and natural decomposition.

Desmond Tutu. [Courtesy]

In aquamation, the body is submerged in an alkaline solution in a metal chamber and heated until it dissolves. This leaves only the bones which are baked and ground to a powder to be returned to the family.

"You're supposed to go in the ground right? You're supposed to be buried, not put away like that," was 79-year-old Stanley Mini's gut reaction.

A candle is placed at the spot where the ashes of the late Archbishop Emeritus Desmond Tutu are laid to rest, at the St George's Cathedral in Cape Town, South Africa. [Reuters]

Aquamation is increasingly popular in some countries like the United States, but in Africa, where burial is the tradition, it was an unusual choice.

"I was like: how did the Arch come to know of aquamation?" said Pieter van der Westhuizen, general manager of one of South Africa's largest funeral homes Avbob, which was used by the Tutus, referring to Tutu by his affectionate nickname.

AVBOB Maitland Funeral Parlour, the only funeral service that performs aquamation in Cape Town, South Africa. [Reuters]

"We (didn't) know ... how big he was on going green. I was very glad to hear that," he told Reuters TV.

Aquamation advocates say its avoids the emission of climate-warming gases produced by cremation and uses 90% less energy.

A mortuary trolley is placed next to the Aquadome machine, a stainless-steel chamber used for aquamation at the AVBOB Maitland Funeral Parlour in Cape Town, South Africa. [Reuters]

"I would choose water - I actually feel good about him choosing water instead of fire," said Cape Town resident Cameron Ruiters, 22.

Following aquamation, Tutu's remains were interred in an wooden box beneath the floor of St George's Cathedral in Cape Town.