[1] Stoychev has 11 consecutive titles of a major international open water marathon swimming FINA series since 2001 (World Cup winner 2001–2006, Grand Prix winner 2007–2011) with more than 60 wins in individual swimming marathons.

Also, he has won the Ohrid Lake, North Macedonia swimming marathon 11 consecutive times (30 km).

English Channel Swims Petar Stoychev won the first place at 2011 World Aquatics Championships in Shanghai, China during the 25 km event, thus becoming the first Bulgarian swimmer with a World Championship title.

He was inducted in the International Marathon Swimming Hall of Fame in Fort Lauderdale, Florida in September 2009.

In September 2024, he repeated his English Channel swim to reduce total time and set the world record for fastest completed Oceans Seven.