According to the latest information available, the Diamond Lake Campground - M Loop boat ramp is located in Oregon and provides access to Diamond Lake. This boat ramp is a concrete ramp and is reportedly wide enough to accommodate most boat trailers.

Diamond Lake is a large body of water, covering approximately 2,824 acres, and is known for its excellent fishing opportunities. The lake is located within the Diamond Lake Recreation Area, which is managed by the U.S. Forest Service.

As for the kind of craft permitted on the water, the latest information indicates that motorized boats are allowed on the lake, but there are restrictions on the size of the motor. Boats with motors larger than 10 horsepower are not permitted, and the use of personal watercraft such as jet skis is also prohibited.

It is important to note that regulations and restrictions can change, and it is always best to check with the local authorities or the managing agency for the most up-to-date information before heading out on the water.