[3] On 18 October 2019, Zecchini became the first woman to have reached a depth of −100m[4][2] exclusively with the use of her arms (free immersion), during the "Nirvana Oceanquest" in Curaçao, Dutch Caribbean.

The same year, Zecchini used the guide rope to pull herself down to a depth of −81 m (−266 ft) without using ballast or fins and thereby set a new world record in the free immersion discipline recognized by the CMAS.

[7] At the Italian Depth Championship in Ischia, she achieved her first CMAS world record in constant weight with the monofin (CWT) with −81 m (−266 ft).

During the Italian depth championship in Ischia, she achieved her second CMAS world record[3] in constant weight with the monofin (CWT) with −86 m (−282 ft).

In 2015, Zecchini took part in the CMAS Indoor[3] World Championship in Mulhouse and, together with her partner Ilaria Bonin, they won five gold and silver medals.

[9] In 2017, the Italian began her outdoor training with international coach and safety diver Stephen Keenan and beat the AIDA world record with −104 m (−341 ft) depth in the Vertical Blue competition on 10 May on Long Island in the Bahamas.

During the last days of the competition, Natalia Molchanova's record in constant weight (CWT) of −101 m (−331 ft) (which had been held for six years), was beaten three times.

[11] The official AIDA report stated that reasonable precautions had been taken; however, it noted that there was no on-site specialist doctor, insufficient medical equipment, no safety boat, and no ambulance[13] on stand-by at the dive site.

[11] Zecchini was experienced in open waters, was familiar with the Blue Hole, and wanted to tackle it without fins rather than with the usual, more powerful mono-fin.

In 2018, Zecchini set the new AIDA world record in constant weight (CWT) on 10 May in San Andrès in Colombia in the Nirvana Oceanquest Freediving Competition.

[22] During the Nirvana Oceanquest 2019 event in Curaçao, she set two world records in the discipline of free immersion under the aegis of AIDA with −98 m (−322 ft) on 16 October 2019.

[28] On 24 May she became again the deepest woman in the world, setting the WR in constant weight with monofin to -123m, during the AIDA Oceanquest Competition in Camotes Island, Philippines.