Spirit Lake, IA (Northwestiowanow.com) — The Iowa Department of Natural Resources is investigating a Saturday night boat accident on East Lake Okoboji.

Around 7pm a 42 foot Catamaran racing style boat operated by 73 year old Duane Vermeer from Spirit Lake struck, a hoist holding another boat, came ashore and crossed 255th Avenue between The Narrows and Stony Point and came to rest upside down.

Vermeer and his passenger – 68 year old Lisa Vermeer of Spirit Lake – were transported to Lakes Regional Healthcare and both transferred to Sioux Falls.

The Iowa State Patrol, Dickinson County Sheriff’s Department, Spirit Lake Police Department, and Spirit Lake Fire and Rescue assisted at the scene.

No cause has yet been determined by investigators.