More than 100,000 security guards have been deployed this year to discourage crime and help control the crowds.
Hajj is one of the five pillars of Islam and it is mandatory for all able-bodied Muslims with the financial means to undertake it once in their lifetimes.
"The day of Arafat is a major event in Hajj," Al Jazeera's Hashem Ahelbarra, said from Arafart.
"Muslims believe that this day resembles - in one way or another - the hereafter, where all human beings will stand before God for their final judgement."
As the sun sets, pilgrims will journey to the valley of Muzdalifa, a few kilometres away, for the night before returning to Mina in the morning.
On Monday, as Muslims around the world celebrate Eid al-Adha (Feast of the Sacrifice), pilgrims performing Hajj cast pebbles at a pillar on the Jamaraat Bridge in Mina, in a symbolic renunciation of the devil.
This stoning ritual continues over the next two days before Hajj draws to a close.
Saudi Arabia places strict controls on the number of pilgrims entering the country - giving a quota to each government, who then select pilgrims.
But in the occupied Palestinian Territories the process encountered difficulties due to there being two de facto governments - Hamas in the Gaza Strip and Fatah in the West Bank.
Mahmoud Abbas, the Fatah-aligned Palestinian president, attacked Hamas for not allowing Palestinians to leave Gaza.
"This is the third time in the history of Islam that the pilgrims are stopped from coming to Mecca," Abbas said while performing Hajj.
"The first time they were prevented to come was in the era of Quraish infidels and the second time were during the Qarmatians time and unfortunately the third time were in the time of Hamas."
Hamas officials say they are not to blame, and object that their list of pilgrim applicants were not granted any Saudi visas, while applicants from the Fatah-backed West Bank's government were granted them.