Last updated October 2026
Cass Bay is a small, sheltered beach on the northern side of Whakaraupō Lyttelton Harbour, west of Lyttelton and about 9 kilometres from central Christchurch.
Christchurch City Council describes it as a sheltered swimming beach with a playground, and the Head to Head Walkway runs through the bay. Environment Canterbury tests the water at two points on the beach every week over summer.
The mid-beach site holds a Fair long-term grade on LAWA, which means it is usually fine for swimming but best avoided after rain, while the newer main beach site has not yet had enough routine tests for a grade. Cass Bay is one of the few Lyttelton Harbour bays that health officials still list as suitable for swimming.
Practical Information
- Location
- Motu-kauati-rahi / Cass Bay, Whakaraupō Lyttelton Harbour, between Corsair Bay and Rāpaki
- Distance from Christchurch
- About 9 km from the city centre
- Water
- Sheltered harbour beach, tidal (nearest tide station: Lyttelton)
- Water quality
- Fair at the mid-beach site (LAWA long-term grade, summers 2020/21 to 2024/25); main beach site not yet graded
- Testing
- Weekly from November to March by Environment Canterbury, at two points on the beach
- Facilities nearby
- Playground, parking, toilets and showers, all within about 60 m of the beach
- Dogs
- Not allowed on Cass Bay Beach from 1 November to 31 March, 9am to 7pm; under effective control at other times (Christchurch City Council)
- Walking
- The Head to Head Walkway passes through the bay
Swimming Facts
Today at Cass Bay
Friday 13 NovemberWater quality track record
Stay out of the water for 48 hours after heavy rain.Fair at 1 testing spot, No grade at 1 (2020 to 2026)ShowHide
What the grades mean
Excellent and Good: rarely unsafe for swimming. Fair: usually fine, but avoid swimming after rain. Poor: often unsuitable, especially after rain, so check the latest result first.
Grades use LAWA’s method: the 95th percentile of routine enterococci (sea) or E. coli (fresh water) results over the five summers from 2021/22 to 2025/26, with at least 50 tests (Cass Bay Mid beach: 369 per 100 mL from 74 tests).
About Cass Bay
Cass Bay is one of a string of small bays along the northern shore of Whakaraupō Lyttelton Harbour, below the Port Hills. Its neighbour to the east is Corsair Bay, and to the west lies Rāpaki.
Christchurch City Council uses the dual name Motu-kauati-rahi / Cass Bay, while Corsair Bay is Motu-kauati-iti. The beach is small and looks out across the harbour, and the council’s playground sits at its western end on Bay View Place.
The English name honours Thomas Cass, the pioneer surveyor who was Chief Surveyor of Canterbury from 1851 to 1867. According to the 1966 Encyclopaedia of New Zealand, now published by Te Ara, both Cass Bay and Cass Peak in the Port Hills are named after him.
The bay is a stop on the Head to Head Walkway, the council’s track around the inner harbour. From Corsair Bay the track becomes narrow and steep in a few places as it climbs around to Cass Bay. Towards Lyttelton, the council suggests a five-minute detour to the Torpedo Boat Museum and Magazine Bay, which it calls a local favourite.
Cass Bay has kept its swimming record while several of its neighbours have not. Environment Canterbury has graded Corsair Bay, Diamond Harbour Beach, Rāpaki Bay and Purau Bay as not recommended for swimming since the end of the 2021/22 season, and in early 2025 Te Whatu Ora named Paradise Beach, Church Bay and Cass Bay as the harbour sites that remained suitable. That makes Cass Bay one of the better choices for a swim in the inner harbour, as long as you check the latest result first.
Swimming and Water Quality at Cass Bay
Environment Canterbury samples Cass Bay every week from November to March and publishes the results on LAWA. There are two testing points on the beach. The mid-beach site has a Fair LAWA long-term grade, based on 75 routine tests over the summers of 2020/21 to 2024/25.
Across 153 tests between November 2019 and April 2025, 88% were suitable for swimming. A Fair grade means the water is usually fine, but bacteria levels can rise after rain, so it is best avoided at those times.
The second point, Cass Bay / Motu-kauati-rahi at the main beach, was added in January 2023. It has not yet had enough routine tests over five summers for LAWA to give it a long-term grade.
Of its 110 tests between January 2023 and April 2025, 83% were suitable for swimming. Testing has run into April in recent seasons, and the final samples of the 2024/25 season, taken on 30 April 2025, were unsuitable at both points. Results can change from week to week.
Environment Canterbury says the small, shallow bays of Lyttelton Harbour make any discharge more likely to affect water quality. It has been working with Christchurch City Council on a multi-year investigation into the sources of faecal contamination in the harbour, which has found streams and stormwater outfalls among the inflows.
You can help by using the public toilets, putting young children in swim nappies and picking up after dogs. When high bacteria levels are found, the public health service may issue a temporary warning until the water improves.
Check the latest result on LAWA before you swim, and stay out of the water for at least 48 hours after heavy or prolonged rain. Environment Canterbury also suggests a toe test: if you cannot see your toes when standing knee-deep, do not swim.
The bay is tidal, so the depth and the amount of beach change through the day. Never swim alone, keep young children within reach, and look out for underwater objects and sudden drop-offs before jumping in.
Getting There and Facilities
Cass Bay is on the harbour side of the Port Hills, about 9 kilometres from central Christchurch and a short distance west of Lyttelton. Parking, the playground, toilets and showers are all within about 60 metres of the beach, so it suits a family outing with young swimmers. The nearest tide station is at Lyttelton, about 2 kilometres away.
You can also arrive on foot along the Head to Head Walkway from Corsair Bay. The council notes that the walkway is buggy-accessible as far as Corsair Bay, but the section on to Cass Bay is narrow and steep in places.
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Frequently Asked Questions
Can you swim at Cass Bay?
Yes. Christchurch City Council describes Cass Bay as a sheltered swimming beach, and Environment Canterbury tests the water weekly over summer. Check the latest result on LAWA first, and stay out for at least 48 hours after heavy rain.
What is the water quality like at Cass Bay?
The mid-beach testing site has a Fair LAWA long-term grade for summers 2020/21 to 2024/25, and 88% of 153 tests between November 2019 and April 2025 were suitable for swimming. Fair means it is usually fine but best avoided after rain.
Why does one of the Cass Bay testing points have no grade?
The main beach point was only added in January 2023, so it has not yet had enough routine tests over five summers for LAWA to give a long-term grade. Of its 110 tests to April 2025, 83% were suitable.
When is the water at Cass Bay tested?
Environment Canterbury samples both points weekly from November to March, and results go on LAWA. In recent seasons testing has continued into April.
Is Cass Bay better for swimming than other Lyttelton Harbour bays?
In early 2025 Te Whatu Ora listed Cass Bay, Church Bay and Paradise Beach as the harbour sites that remained suitable for swimming, while Corsair Bay, Rāpaki Bay, Sandy Bay, Diamond Harbour and Purau were unsuitable.
What facilities are at Cass Bay?
There is a playground at the western end of the beach on Bay View Place, with parking, toilets and showers close by.
How far is Cass Bay from Christchurch?
Cass Bay is about 9 kilometres from central Christchurch, on the Lyttelton Harbour side of the Port Hills, just west of Lyttelton.
Can you walk to Cass Bay?
Yes. The Head to Head Walkway links Cass Bay with Corsair Bay and Lyttelton. The section between Corsair Bay and Cass Bay is narrow and steep in a few places.
Spotted something incorrect on this page? Let us know.
Related links 3
- LAWA and Environment Canterbury: the latest “Can I Swim Here?” results and the long-term grade for Cass Bay.
- Environment Canterbury: why some Lyttelton Harbour bays are not recommended for swimming, and which ones are still suitable.
- Christchurch City Council: the Head to Head Walkway brochure, with the track around Corsair Bay, Cass Bay and the inner harbour.
Sources and data notes 2
- Today at Cass Bay: Tides: LINZ, CC BY 4.0; predictions only. Sea temperature: NASA JPL MUR satellite data for 10 Nov, via Tideteller.
- Water quality track record: Water quality: © LAWA and partner organisations (Environment Canterbury), licensed under CC BY 4.0, results to March 2026; latest results on LAWA. Facilities: © OpenStreetMap contributors.