Beginning in 1903, odd artifacts were displayed in hallways and alcoves in Portland City Hall arranged by Colonel L. L. Hawkins.

The need for expansion led volunteers to build a new site at Washington Park, achieving the original goal of establishing a hands-on museum.

Expansion at the Washington Park site was deemed infeasible, and in 1986 it was announced that the museum would move to a new location on the east bank of the Willamette River, where a much larger building would be constructed.

[2] Property that included the historic Station L power plant was donated by Portland General Electric, and building construction was paid for by a fundraising campaign.

In 2004, the Turbine Hall was closed from September through November for renovations in which the Discovery Space and Technology Lab changed places and a new Inventors Ballroom was added.

[8] In 2008, OMSI began finalizing the plans for the expansion, which was estimated to cost about $500 million and would double the size of the museum.

This submarine appeared in the 1990 film The Hunt for Red October before being towed to its present location, a pier adjacent to the museum.

Past exhibits have included "Grossology" (Winter–Spring 2001), "Giants of the Gobi" (1997), "A T-rex named Sue" (September 2001 – January 2002), and "CSI: The Experience" (May–September 2009).

The Life Sciences Laboratory houses a wide variety of live animals, such as rats, walking sticks, chameleons, Madagascar hissing cockroaches, other mammals, reptiles, amphibians, and insects.

Volunteers and staff members demonstrate and lead a variety of a group activities such as owl pellet dissections and exploration of the differences between male and female skulls and pelvises.

The Science Playground, in the early childhood education area on the second floor of the museum, is designed for families with newborn to six-year-old children.

There is also a Parent Resource Corner with reference materials on topics ranging from the developing brain to behavior intervention techniques.

Visitors can crawl through the roots of a discovery tree, look for animals in a cave and a chipmunk den, play in a woodland stream, and be a naturalist for a day.

Computer-aided astronomy and laser light shows are performed daily in the Harry C. Kendall Planetarium (previously the M. J. Murdock Sky Theater).

Located alongside the Willamette River in the Central Eastside Industrial District, the restaurant has 9,100 square feet (850 m2) of dining space.

[52] Mark Patel, former developer director of OMSI, was behind the creation of the restaurant,[53] which is operated by Bon Appétit Management Company.

[55] Theory is located off of the Willamette River, with views of the Tilikum Crossing, Marquam Bridge, and the downtown Portland skyline.

Science fairs that take place in the main auditorium include OHSU's Brain Awareness, Safety Safari, and the Reptile and Amphibian Show.

[60][61] This program is open to industry or academic researchers or science professionals interested in improving their scientific communication, which includes university faculty, graduate students, technicians, or other individuals in science-, engineering-, health-, or technology-related positions.

Fellows who are chosen participate in a series of communication training workshops and develop their own hands-on demonstration based on their work.

Lastly, fellows participate in OMSI's Meet a Scientist program to engage with the museum visitors with their demonstration.

OMSI is a non-profit organization and is funded by admissions, member contributions, public and private donations, community agencies, federal grants, and fundraising events.

[citation needed] The Teen Science Alliance, OMSI's youth volunteer program, takes place both during the summer and during the school year.