A NSW coroner is among the Splendour in the Grass attendees as the major music festival plays host to a drug-checking demonstration.

Deputy State Coroner Harriet Grahame, who is overseeing the inquest into six recent drug-related deaths at NSW music festivals, today toured the festival near Byron Bay in the state's north.

More than 35,000 people were expected to attend the second day of the three-day event at North Byron Parklands in Wooyung.

Over 35,000 people are expected at Splendour in the Grass this weekend as the NSW Coroner in charge of the music festival deaths inquest oversees a pill-testing trial at the event. (AAP)

A high-visibility police operation is in place over the three days targeting illegal drug use and supply, alcohol-fuelled violence and anti-social behaviour.

Ms Grahame received a private police briefing at 9am before meeting with harm minimisation group Red Frogs.

She also had a front-row seat as David Caldicott - an emergency medicine specialist and the leader of Australia's only sanctioned pill testing trials - demonstrates how drug checking works.

NSW does not currently permit testing of illicit drugs at music festivals, meaning Dr Caldicott will only demonstrate using legal substances.

The coroner is overseeing the the inquest into the deaths of Alex Ross-King, Nathan Tran, Diana Nguyen, Joseph Pham, Joshua Tam and Callum Brosnan, who died between December 2017 and January 2019.

All were under the age of 24 and died after consuming MDMA at NSW music festivals.

The inquest, which will resume in September, has been told drug checking would offer a chance for young people to be counselled on their use of illicit drugs and warned of the harms.

Arguments for and against pill-testing run hot as drug dogs and a heavy police presence continue at Australia music festivals after recent deaths of young people from suspected overdoses. (AAP)

The NSW Coroner in charge of the music festival drug deaths inquest will oversee a pill-testing trial at Splendour in the Grass today. (AAP)

Various methods have been proposed, including spot-test kits at music festivals and establishing a permanent laboratory in an urban centre capable of offering anonymous drug checking to all.

For now, with drug possession and supply outlawed, police have warned those at Splendour to be aware of the consequences of risky behaviour.

"Festival-goers who choose to do the wrong thing not only compromise their own safety, but also risk the safety of others around them," Superintendent Dave Roptell said in a statement.

"Prohibited drugs are illegal and potentially life-threatening, especially when combined with alcohol, so I urge everyone to behave responsibly.

"Anyone under the influence, or who feels unwell, is urged to seek professional medical attention."