Understanding what the sea is doing before you travel makes the difference betwen a smooth crossing and an uncomfortable one. The index below updates every 30 minutes with live conditions for the Bali to Lombok to Gili crossing.

Gili Marine Index: sea conditions before you cross

SEA CONDITIONS

LIVE RIGHT NOW

READING THE INDEX

What each rating actually means

There is no single number that defines rough for every traveller, tolerance varies a lot between people. That is why the index gives a plain-language rating alongside the raw numbers rather than swell height and wind speed on their own.

GREEN

Calm conditions

Small, well-spaced swell

Light wind and gentle swell working together. The kind of morning where most passengers barely notice the motion.

WHAT TO DO

Travel with confidence at any departure time.

AMBER

Moderate conditions

Larger or closer-together swell

Occasional spray over the bow and enough movement that anyone prone to seasickness will feel it.

WHAT TO DO

Choose a morning sailing and sit mid-boat.

RED

Rough conditions

Large swell, strong wind

Operators may adjust routes, delay departures, or in some cases suspend crossings entirely until conditions ease.

WHAT TO DO

Check directly with your operator before you travel.

THE TWO NUMBERS THAT MATTER

Swell and wind, and why they differ

Both affect the crossing, but not in the same way. Knowing which one is driving today's rating tells you what the ride will actually feel like.

What is swell

Swell is the height and rhythm of waves moving across open water, separate from local wind chop on the surface. A boat handles a longer, gentler swell far more comfortably than the same wave height arriving in short, sharp intervals.

Swell height tells you roughly how much the boat will rise and fall. Swell period, the gap between waves, tells you how smooth or jarring that motion will feel.

Rule of thumb: a longer period at the same height is a noticeably easier ride.

What is wind

Wind affects the crossing differently than swell does. Strong wind against the direction of travel creates chop on top of the existing swell, making the surface choppier and less predictable even when the underlying swell is moderate.

Wind direction relative to your route matters as much as wind speed.

Rule of thumb: a crossing directly into a headwind feels rougher than the same wind speed from behind or the side.

Is today safe for children

Operators generally continue running in calm to moderate conditions, and children cross safely on these routes every day. The main considerations are comfort rather than safety. Smaller children can find prolonged rougher motion more distressing than adults do, and seasickness affects children more noticeably.

If the index shows rougher conditions on your travel day, a morning departure will usually give a smoother crossing than an afternoon one. It is also worth discussing with your operator whether a larger, more stable vessel is available if that matters for your family.

TIMING YOUR CROSSING

Morning or afternoon?

Wind tends to build through the day, so the same route can feel very different depending on when you sail.

Morning crossings

Consistently calmer across this route. A departure before mid-morning generally means less chop, even on days with otherwise similar swell. If you have a choice of departure time and are at all concerned about the crossing, morning is the safer default.

EXPECT MORE MOVEMENT

Afternoon crossings

Wind builds through the day, so afternoon sailings typically bring more chop on top of the underlying swell. Still routine for most travellers, but less ideal if anyone in your group is prone to motion sickness.

ACROSS THE YEAR

Best time of year to cross

Sea conditions follow a broad seasonal pattern, though the daily forecast still matters more than the averages.

MAY TO OCTOBER

Dry season

The calmest and most consistent sea conditions for this crossing, with visibility and comfort both at their best.

NOVEMBER TO APRIL

Wet season

Still plenty of calm days, but conditions are less predictable, afternoon weather in particular.

MAY, JUNE, SEP, OCT

Shoulder months

Often the best balance of calm seas without the peak season crowds.

Worth remembering: whatever time of year you travel, the index shows a five-day outlook alongside current conditions. If you are crossing in the next few days, check the forecast strip rather than relying on seasonal averages alone.

Understanding what the sea is doing before you travel makes the difference betwen a smooth crossing and an uncomfortable one. The index below updates every 30 minutes with live conditions for the Bali to Lombok to Gili crossing.

Gili Marine Index: sea conditions before you cross

SEA CONDITIONS

LIVE RIGHT NOW

READING THE INDEX

What each rating actually means

GREEN

Calm conditions

Small, well-spaced swell

Light wind and gentle swell working together. The kind of morning where most passengers barely notice the motion.

WHAT TO DO

Travel with confidence at any departure time.

AMBER

​Moderate conditions

Larger or closer-together swell

Occasional spray over the bow and enough movement that anyone prone to seasickness will feel it.

WHAT TO DO

Choose a morning sailing and sit mid-boat.

RED

Rough conditions

Large swell, strong wind

Operators may adjust routes, delay departures, or in some cases suspend crossings entirely until conditions ease.

WHAT TO DO

Check directly with your operator before you travel.

THE TWO NUMBERS THAT MATTER

Swell and wind, and why they differ

What is swell

​Swell is the height and rhythm of waves moving across open water, separate from local wind chop on the surface. A boat handles a longer, gentler swell far more comfortably than the same wave height arriving in short, sharp intervals.

Swell height tells you roughly how much the boat will rise and fall. Swell period, the gap between waves, tells you how smooth or jarring that motion will feel.

Rule of thumb: a longer period at the same height is a noticeably easier ride.

What is wind

Wind affects the crossing differently than swell does. Strong wind against the direction of travel creates chop on top of the existing swell, making the surface choppier and less predictable even when the underlying swell is moderate.

Wind direction relative to your route matters as much as wind speed.

Rule of thumb: a crossing directly into a headwind feels rougher than the same wind speed from behind or the side.

Is today safe for children

If the index shows rougher conditions on your travel day, a morning departure will usually give a smoother crossing than an afternoon one. It is also worth discussing with your operator whether a larger, more stable vessel is available if that matters for your family.

TIMING YOUR CROSSING

Morning or afternoon?

RECOMMENDED

Morning crossings

Consistently calmer across this route. A departure before mid-morning generally means less chop, even on days with otherwise similar swell. If you have a choice of departure time and are at all concerned about the crossing, morning is the safer default.

EXPECT MORE MOVEMENT

Afternoon crossings

Wind builds through the day, so afternoon sailings typically bring more chop on top of the underlying swell. Still routine for most travellers, but less ideal if anyone in your group is prone to motion sickness.

ACROSS THE YEAR

Best time of year to cross

MAY TO OCTOBER

Dry season

The calmest and most consistent sea conditions for this crossing, with visibility and comfort both at their best.

NOVEMBER TO APRIL

Wet season

Still plenty of calm days, but conditions are less predictable, afternoon weather in particular.

MAY, JUNE, SEP, OCT

Shoulder months

Often the best balance of calm seas without the peak season crowds.

Moderate conditions

Swell is the height and rhythm of waves moving across open water, separate from local wind chop on the surface. A boat handles a longer, gentler swell far more comfortably than the same wave height arriving in short, sharp intervals.