Definition (活動)
When an event is in full swing, it means it has been underway for some time and is at its most active and energetic stage.
正在高潮（事件）
The party was in full swing when we arrived.
我們到達時，派對正進行得如火如荼。
The International Film Festival was in full swing when we arrived.
我們到達時，國際電影節正進行得如火如荼。
Cinco De Mayo festivities are currently in full swing.
五月五日節慶祝活動目前正進行得如火如荼。