Beach blobs: Jellyfish and tar are common hazards on local beaches. Matthew King

Memorial Day traditionally marks the kickoff of prime beach-going season. The shoreline is indeed a magnificent getaway. But as with any decent playground, dangers lurk. Here’s some advice for staying out of harm’s way this summer.

The good news is that water quality at local beaches continues to be very good, with 91% of L.A. County beaches receiving an A or B grade in the summer in Heal the Bay’s latest Beach Report Card. But bacteria-polluted hot spots remain. It’s a good idea to swim at least 100 yards from piers, storm drains and creek/river mouths. Think the length of a football field.

Summer brings south swells to Santa Monica Bay, which can trigger pounding surf. If the waves look overwhelming to you or your family, they probably are. Play it safe and stay close to shore. If you do go in, dive underneath big waves, almost skimming the ocean floor, instead of trying to swim through or jump over them. If you surf, admit your limitations and don’t put yourself needlessly in danger.

If you are caught in a rip current, don’t fight it. Instead, swim parallel to shore for a few yards until you are free from its grip. Then you can safely swim to shore when you reach calmer water. Many people exhaust themselves flailing in place trying to swim directly to shore, necessitating a guard rescue. To identify rips, look for unusual gaps as waves break and create whitewater that sucks out back to sea. The water is usually sandy/discolored and choppy on the surface.

Jellies float through the ocean carried by currents, so they don’t seek human contact. But when certain species bump into swimmers, venom stored in sacs on their wavy legs can cause significant irritation. Wearing a long-sleeve rash guard offers some protection. If you are stung, applying white vinegar can help denature the toxins released by the animals. And don’t let your kids play with dead jellyfish on the shore; they can still sting.

Stingrays are actually members of the shark family, and are attracted to the warm shallows of the Bay during summer. Rays will pump venom into your body, much like a bee, If you step on or get hit by their barbs. The sting is extremely painful (trust me, I got nailed right off the Jonathan Club recently.) The only relief comes from soaking your foot in very hot water to disperse the toxins. Doing the stingray shuffle – sliding your feet on the ocean floor as if on skis – can help you avoid this fate.

Yes, there are white sharks in the Bay. No, it’s highly unlikely that you’ll ever see one or be bothered by them. Whites spotted in our waters recently are smaller juveniles. They are feeding on bottom fish not mammals. There have only been 11 fatal white shark encounters in ALL of California since the 1980s. Eating a hot dog is more dangerous, statistically, than taking a swim in the ocean. And those leopard sharks you see skittering in the shallows? Don’t worry about them. Their mouths are about the size of a quarter and they like to nibble on sand crabs, not toes.

Algal blooms that pop up in the Bay during warmer months turn the sea to a rust tint. The water isn’t polluted. It’s just filled with millions of phytoplankton. Some species can produce toxins that can harm local marine life or poison shellfish (thus the advice to avoid mussels and clams during summer). While not toxic to humans, blooms can cause eye and skin irritation for swimmers. My advice if you see a bloom? Pick a different swim spot.

Black sticky clumps of tar on the beach are typically NOT from oil tankers or offshore drilling. Instead they come from natural oil seeps on the ocean floor, triggered by normal geological activity. On average, about 420 gallons of oil from local seeps reach the sea surface daily in Santa Monica Bay. The globs then wash onshore. While they are natural, tarballs can be a real pain when stepped on. The best way to remove beach tar from the bottoms of your feet is to rub a little olive oil on them. Skip the gasoline or other toxic solvents.

People holding up the line by taking three-minute beach showers, meticulously washing and re-washing every body part as if any stray particles of sand left on their bodies were potentially radioactive?
Numbskulls riding electric scooters on the water’s edge? IG-conscious wanna-bes who take up surfing but are too self-absorbed to learn basic etiquette as they snake your wave? Sorry, you’re on your own …

More diversity: Historian Alison Rose Jefferson sent me a note reminding me that Nick Gabaldon may have been one of L.A. County’s first recognized surfers of color but he did not serve as a lifeguard. Also, the Black Surfers Collective is hosting a “Black Out at Bay Street” family gathering on June 19, from 9 a.m. to noon. All beach lovers are encouraged to drop by Tower 20 and say hello. I’ll be there.

Matthew King grew up on the beaches of Santa Monica, where his father served as a County lifeguard for 30 years. He sneaks away from his communications and marketing consultancy as often as he can to surf Bay Street and other local breaks.