Hundreds attended a rally by Seif Sharif Hamad of the opposition Alliance for Change and Transparency, ahead of Tanzania's general election on Wednesday.
Hamad is vying for the presidency of Zanzibar, a semi-autonmous archipelago ruled by Dar-es-salaam.
But Zanzibar, just as mainland Tanzania has been hostile ground for the opposition. Just before Hamad's rally, the party's chief campaigner on the island went missing before re-emerging on Sunday afternoon.
Nassor Ahmed Mazrui was allegedly abducted by unknown people who held him captive for five hours.
The opposition is hoping to unseat president John Magufuli, who since coming to power in 2015, has stifled political and civil liberties according to activists.
"Life is tough and the union is really crushing us, they don’t give any right to Zanzibarians, they only break us Zanzibarians. It prevents Zanzibar from having a good life and [from] growing," said Sherif Moussa Faki, bus driver and opposition supporter.
The opposition, headed by Tundu Lissu- the Chadema presidential candidate, hopes to turn the anger of supporters like Faki into votes.
President Magufuli's Chama Cha Mapinduzi (CCM) party has dominated Tanzanian politics since independence.
Twenty seven (27) million people are eligible to vote on Wednesday.
Magufuli has promised to create jobs for Tanzania's youth by stepping up investment in infrastructure projects.
Lissu on the other hand has promised to tackle corruption, draft a new constitution and to deregulate business and foreign investment.
Both the opposition and ruling party camps have been holding big rallies without concerns for the pandemic. President Magufuli has said there's no virus in the East African country.