Vaiavasvata Manu lives in Ramayana Varsha, as described in this chapter of the Sriman Bhagavatam:
In Ramyaka-varṣa, where Vaivasvata Manu rules, the Supreme Personality of Godhead appeared as Lord Matsya at the end of the last era [the Cākṣuṣa-manvantara]. Vaivasvata Manu now worships Lord Matsya in pure devotional service and chants the following mantra. "I offer my respectful obeisances unto the Supreme Personality of Godhead, who is pure transcendence. He is the origin of all life, bodily strength, mental power and sensory ability. Known as Matsyāvatāra, the gigantic fish incarnation, He appears first among all the incarnations. Again I offer my obeisances unto Him. My dear Lord, just as a puppeteer controls his dancing dolls and a husband controls his wife, Your Lordship controls all the living entities in the universe, such as the brāhmaṇas, kṣatriyas, vaiśyas and śūdras. Although You are in everyone’s heart as the supreme witness and commander and are outside everyone as well, the so-called leaders of societies, communities and countries cannot realize You. Only those who hear the vibration of the Vedic mantras can appreciate You. My Lord, from the great leaders of the universe, such as Lord Brahmā and other demigods, down to the political leaders of this world, all are envious of Your authority. Without Your help, however, they could neither separately nor concertedly maintain the innumerable living entities within the universe. You are actually the only maintainer of all human beings, of animals like cows and asses, and of plants, reptiles, birds, mountains and whatever else is visible within this material world. O almighty Lord, at the end of the millennium this planet earth, which is the source of all kinds of herbs, drugs and trees, was inundated by water and drowned beneath the devastating waves. At that time, You protected me along with the earth and roamed the sea with great speed. O unborn one, You are the actual maintainer of the entire universal creation, and therefore You are the cause of all living entities. I offer my respectful obeisances unto You."
But if you want to know where Ramyaka Varsha is, good luck. I can tell you that Ramyaka Varsha is in the Northern portion of Jambu Dvipa, as opposed to Bharata Varsha which is on the Southern portion. But the thing is, different people have different views of Hindu cosmology. Many people (myself included) think the seven Dvipas are the seven continents, Jambudvipa is the continent India is a part of, and Bharatavarsha is the Indian subcontinent. But others think that Jambudvipa is the entire Earth, and the other Dvipas are outside the Earth. And still others think that Bharatavarsha is the entire Earth, Jambudvipa is bigger than that, and Bhuloka is even bigger than that. So depending on who's right, Vaivasvata Manu may or may not reside on the Earth.