The Fourth of July weekend got off to a busy start Saturday with numerous rescues at sea and on land across Oahu.

>> A 57-year-old woman suffered a serious back injury after jumping about 50 feet at Maunawili Falls, Emergency Medical Services reported.

EMS said the woman jumped into the pool below the falls.

The Honolulu Fire Department airlifted the woman to a nearby park, where EMS treated and transported her in serious condition to a hospital at 12:34 p.m.

On Tuesday, Honolulu firefighters rescued a 48-year-old woman with an injured ankle from the Maunawili Falls Trail.

>> On Saturday, around 1:16 p.m., a 17-year-old girl slipped and fell while hiking along the Waahila Ridge Trail, HFD and EMS said.

HFD said the girl was hiking with her father when she slipped and fell along a muddy trail and hurt her back.

The hiker walked out on her own to her car and declined medical treatment, EMS said.

>> Ocean Safety, the Honolulu Fire Department and EMS responded at 1:45 p.m. to a swimmer at China Walls, but the female visitor managed to get out on her own without injury.

The agencies again responded to a call at 2:28 p.m. to another swimmer in distress off Spitting Cave.

HFD sent 12 personnel and the first firefighters on scene were there at 2:36 p.m., but the location was China Walls.

Good Samaritans assisted a man and woman to safety and no medical attention was needed.

>> Lifeguards towed a broken watercraft and its operators to safety at 2:15 p.m. a mile off Alii Beach Park. No one was injured.

Ocean Safety urged beachgoers and swimmers to know their limitations, watch children closely and not drink alcohol if going into the water.

People were also warned to stay away from shorelines when there is surf; and carry a cellphone and call 911 immediately if someone is in distress.

HFD warns people not to climb on wet rocks or ledges, which indicates a wave recently washed over them and could become slippery or a wave could hit and knock someone over; stay within your fitness and swimming abilities; and avoid moving water, waves or rip currents.