His best known victory was part of the 4 x 10 km relay team that upset Norway at the 1994 Winter Olympics in Lillehammer, when he was 43 years old. Eighteen years earlier, at the 1988 Winter Olympics in Calgary, De Zolt carried the Italian flag during the opening ceremonies. De Zolt was formerly a firefighter, and once placed second in ladder climbing at the World Fireman Championships.
1977: 1993:.
1977: 1st, Italian men"s championships of cross-country skiing, 50 km 1978: 3rd, Italian men"s championships of cross-country skiing, 50 km 1979: 1st, Italian men"s championships of cross-country skiing, 50 km 2nd, Italian men"s championships of cross-country skiing, 30 km 2nd, Italian men"s championships of cross-country skiing, 15 km 1980: 2nd, Italian men"s championships of cross-country skiing, 50 km 2nd, Italian men"s championships of cross-country skiing, 15 km 1981: 1st, Italian men"s championships of cross-country skiing, 50 km 1st, Italian men"s championships of cross-country skiing, 30 km 2nd, Italian men"s championships of cross-country skiing, 15 km 1982: 1st, Italian men"s championships of cross-country skiing, 30 km 1st, Italian men"s championships of cross-country skiing, 15 km 1983: 1st, Italian men"s championships of cross-country skiing, 30 km 1st, Italian men"s championships of cross-country skiing, 15 km 1984: 1st, Italian men"s championships of cross-country skiing, 50 km 1st, Italian men"s championships of cross-country skiing, 15 km 2nd, Italian men"s championships of cross-country skiing, 30 km 1985: 1st, Italian men"s championships of cross-country skiing, 50 km 1st, Italian men"s championships of cross-country skiing, 15 km 2nd, Italian men"s championships of cross-country skiing, 30 km 1986: 1st, Italian men"s championships of cross-country skiing, 50 km 1st, Italian men"s championships of cross-country skiing, 30 km 1987: 1st, Italian men"s championships of cross-country skiing, 50 km 2nd, Italian men"s championships of cross-country skiing, 15 km 3rd, Italian men"s championships of cross-country skiing, 30 km 1988: 1st, Italian men"s championships of cross-country skiing, 50 km 3rd, Italian men"s championships of cross-country skiing, 15 km 1989: 2nd, Italian men"s championships of cross-country skiing, 50 km 3rd, Italian men"s championships of cross-country skiing, 30 km 1990: 3rd, Italian men"s championships of cross-country skiing, 50 km 1991: 2nd, Italian men"s championships of cross-country skiing, 50 km 3rd, Italian men"s championships of cross-country skiing, 30 km 1992: 1st, Italian men"s championships of cross-country skiing, 50 km 2nd, Italian men"s championships of cross-country skiing, 30 km 2nd, Italian men"s championships of cross-country skiing, 15 km 3rd, Italian men"s championships of cross-country skiing, 10 km 1993: 3rd, Italian men"s championships of cross-country skiing, 30 km 1994: 1st, Italian men"s championships of cross-country skiing, 50 km 2nd, Italian men"s championships of cross-country skiing, 30 km.
