Deer joined Fred Olsen in 2004 as commercial director and rose to become managing director in 2019.
However, in October 2023, Samantha Stimpson was named chief executive, joining from German operator FTI, with Deer then moving to the post of chief financial officer.
In a statement, Fred Olsen said Deer would spend the summer with his family before seeking new opportunities.
Stimpson added: “I am grateful to Pete for his significant contribution to the business over his 20-year tenure, and specifically the guidance he has offered since I joined the business in February.
“I wish him a relaxing summer and prosperous future career as my team and I continue to grow and modernise Fred. Olsen Cruise Lines.”
