Gilman Hot Springs, also known as San Jacinto Hot Springs or the Relief Springs, is a hot spring system in the Inland Empire area of Southern California. Located near Potrero Creek, the San Jacinto River, and California State Route 79, the springs system consists of "about half a dozen" springs named for the Mexican land grant Rancho San Jacinto Viejo.

The springs emerge from a granitic alluvium formation that formed a marsh area. Gilman Hot Springs, along with Eden Hot Springs and Soboba Hot Springs, was one of a cluster of geothermally heated water sources along a fault line at the western base of the San Jacinto Mountains.

According to one account, "Indians" used the springs to clean off sheep prior to shearing. According to another, the Cahuilla peoples slept in the springs in winter, up to their necks, to keep warm at night. The Branch family began homesteading the property, partially acquired from the Southern Pacific railroad, in 1880 or 1881. Beginning in 1888, Sidney Branch of Riverside developed the springs and built the Relief Springs Hotel there. In 1895 the Los Angeles Times described the retreat as having three springs: the main sulphur spring was 120 °F (49 °C), the mud spring was 114 °F (46 °C), and a secondary water spring was 112 °F (44 °C). The springs resort could be reached via the Beaumont station of the Southern Pacific line, and then via an omnibus the remaining 8 miles (13 km) to the springs. In the 1890s, it was sometimes advertised as Relief Hot Mud Springs.

In 1913, the property was sold for $53,000 ($1,231,135 today) to three brothers: William Earl Gilman (and his wife Josephine), Grant Gilman, and Forest Gilman. They were natives of Topeka, Kansas, and William E. Gilman had previously owned a hotel in Ocean Park that had burned in 1912. The Gilmans changed the name to Gilman Relief Hot Springs and later to Gilman Hot Springs. The original hotel reportedly had just five rooms. Gilman Hot Springs was one of three hot springs resorts near San Jacinto that offered visitors mineral water baths, mud baths and the opportunity to drink the hot mineral waters bubbling up from the San Jacinto Fault, an offshoot of the San Andreas Fault.

In 1913 the Gilman brothers built a bathhouse and a spring-fed swimming pool was built the following year. Later, the pool was expanded to an Olympic size. The resort was said to have a "frame hotel and cottages and tents forming a little settlement in a grove adjacent to the springs. Besides the usual tub baths there are mud baths that use material from the tule marsh". In 1917 a U.S. government geologist reported: "At the Relief group six thermal springs issue from a bank of disintegrated granite, and considerable water also rises in an adjacent marshy area several acres in extent. The place has been a resort for more than 20 years, a frame hotel and cottages and tents forming a little settlement in a grove adjacent to the springs." A fire in the winter 1917 "razed all the original buildings and demolished all the initial improvements the Gilmans had made". The replacement hotel was built with "bricks and timbers salvaged from an old San Jacinto school building".

Many visitors arrived by train via San Jacinto, where they were met by representatives of the hotel to be transported to the resort. In 1930, visitors could get to Gilman's Hot Springs by either taking the Pacific Electric to Riverside and there connecting with a Motor Transit stage, or by taking a Santa Fe Railway train to San Jacinto, where an auto stage would then ferry them to the springs resort. A San Bernardino newspaper columnist later recalled the early years of the resort: "As a youth I used to hunt quail and rabbits along the San Jacinto River and, of course, always retired to Gilman's, where even in those days, there was a lunch counter which did, as I remember, a thriving business. Then, sometime later, my father was a patient at the resort, taking the spring water and mud baths, for a rheumatic condition. I frequently visited him there. He occupied one of the one-room houses, a tiny place. In those days, nobody ever heard of golf, but the buggies and rigs of all types jammed the grounds of the springs."

The resort had its own golf course alongside the San Jacinto River. It was originally opened with nine holes in 1930; the course was later expanded to 27 holes before being destroyed in a flood. Other activities for visitors included hiking in the hills and walks within the resort. The resort had a dance hall, with weekly dances on Fridays accompanied by piano, violin and drums. A variety of events were held at the property such as beauty contests.

By 1940 there were 127 buildings on the property, accommodations for 400, horse stables, and tennis courts. The stable was later converted to a tavern. A service station and garage for use by visitors was added later that decade. In 1943, golf was 50¢ on weekdays, 75¢ on weekends and holidays, rooms cost $1.50 to $4 a night, and spa treatments including Roman mud baths and California tule mud baths. By the end of the 1950s, travel guides also promised "hiking, painting, badminton, horseshoes, ping pong, croquet, square dancing, modern dancing, motion pictures, and all sorts of planned activities and events for both youngsters and their parents". The Riverside Community Book of 1954 described it as a "moderately priced family resort". Guests during the resort's heyday reportedly included Joe DiMaggio and Marilyn Monroe, Sugar Ray Robinson, and an unidentified president of Ireland.