2026.10.26

Seisho Surf Fishing Guide (Kanagawa): Steep Gravel Beaches You Can Reach by Train

minagiman

Seisho, on the west side of Sagami Bay in Kanagawa, is unlike the other surf areas I have covered — not a shallow sand beach but a steep gravel beach. Fish it with a shallow-beach mindset and you will struggle.

Contents

What is Seisho?
100 m deep within 1 km
Oiso divides two seas
How steep water changes the fishing
Species and seasons (unofficial)
Spots
Safety on steep gravel
Kanagawa rules
Tackle
Minagiman’s take
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What is Seisho?

The Seisho coast managed by the national government runs about 13 km from the Sakawa River mouth to Oiso port — roughly what anglers call “Seisho surf”. Sagami Bay has a submarine canyon reaching into the bay, and the government describes it as one of Japan’s steepest seabeds alongside Suruga and Toyama bays.

100 m deep within 1 km

Kanagawa classifies the Odawara coast as a gravel beach: water reaches 100 m deep only 0.5–1 km offshore, the beach is steep, four rivers bring down large stones, and big waves are common. Compare that with Enshu-nada or Kujukuri, where you are in about 2 m of water 40 m out.

Oiso divides two seas

	Seisho (Odawara, Ninomiya)	Shonan (Hiratsuka, Chigasaki)
Bottom	Large gravel	Sand
Slope	Steep (100 m deep at 0.5–1 km)	Shallow

West of Oiso: gravel and steep. East: sand and shallow. Mixing Seisho and Shonan information causes confusion.

How steep water changes the fishing

One fishing site says the water drops past 10 m just beyond the shoreline at Kozu (not an official figure). If so: no need to blast casts to an offshore drop-off — the drop-off is at your feet. Close range is the main battleground, and working the water in front of you beats long casts. Good news for anglers who cannot cast far.

Species and seasons (unofficial)

Season	Species
All year	Whiting, croaker, flounder, flathead
Spring–autumn	Whiting, croaker (bait casting)
Summer–autumn	Young yellowtail, mackerel, frigate tuna
Autumn–winter	Flounder and flathead
Others	Seabass, squid, ribbonfish, mejina, black bream

Spots

Spot	Town	Parking	Train	Notes
Ninomiya / Umezawa	Ninomiya	Free space by the port	Ninomiya stn, 15–20 min walk	Groynes and rock piles
Kozu beach	Odawara	No dedicated parking	Kozu stn, 5–6 min walk	The classic Seisho spot
Sakawa beach / river mouth	Odawara	Free, large (full at dawn)	Kamonomiya stn, 20–30 min	No toilets
Miyuki-no-hama / Odawara port	Odawara	Coin parking nearby	—	Closed areas in the port
Oiso beach / port	Oiso	Paid, 353 spaces (310 yen/h)	Oiso stn, ~10 min	Clear rules
Hiratsuka / Sagami River mouth	Hiratsuka	Paid, ~200	—	Shallow from here east

Seisho’s biggest plus: you can go by train. The JR Tokaido line runs along the coast — rare for surf near Tokyo. Kozu has no real parking, so the train is the best option.

Kozu: 5–6 minutes from Kozu station. Roadside parking near the beach is illegal — use coin parking. In August 2016 a man in his 20s playing at the water’s edge was swept away and found 30 m offshore; he did not survive. Do not wade, stay back from the edge, and wear a life jacket.
Sakawa river mouth: about 680 m of beach east of the mouth, then tetrapods, then another ~700 m. Shallow with rocks near the mouth — snags. Free parking fills at dawn; no toilets (convenience store within 10 minutes). Terrain changes after floods.
Ninomiya / Umezawa: gravel with groynes and rock piles; free space by the port may close — check with the town. Typhoons in 2007 and 2017 destroyed seawalls here — waves can wash over; non-slip shoes and a life jacket are essential.
Odawara port: Kanagawa lists closed areas including breakwaters and tetrapods. Tetrapods here are 7–10 m tall and 20–60 tonnes each, slippery, with gaps you may not get out of. Entering closed areas breaks the Minor Offences Act.
Oiso port: fishing allowed on the inner side of the west breakwater; no climbing fences, no tetrapods, no breakwater access in storms or outside opening hours. Hours vary by month (8:30 to 16:00–18:00). Closed when wave warnings are issued, wind exceeds 13 m/s or white water washes over the west breakwater — a useful go/no-go guide for the surf too.
Hiratsuka: shallow Shonan beach from here east. The adjacent fishing port opens 7:00–17:00, boats have priority, and the car park cannot be used overnight — a trap if you plan to arrive the night before.

Safety on steep gravel

Kanagawa explains rip currents: look for discoloured water, gaps in breaking waves, foam or debris moving out. If caught, do not panic; swim parallel to the shore, or float and wait for help. Combine that with steep water, big waves and the Kozu accident, and the message is clear: do not wade. Cast from a few metres back from the edge — the water is deep enough anyway.

Kanagawa rules

Allowed gear: rod and line, hand lines, landing nets, small rakes (≤15 cm), cast nets, spears and hand collection.
No fish-attracting lights; no crab nets.
Abalone and sea cucumber are banned (up to 3 years’ prison or 30 million yen).
Yellowtail 15 cm or under must be released.
Hiratsuka bans fishing rods in swimming areas during swimming season.

Tackle

Part	Guide
Rod	9’6”–10’6” ML–M (no need for 11 ft+)
Reel	4000
Line	PE 1.0–1.2
Leader	Fluoro 25–30 lb (gravel abrades it)
Lures	~30 g is enough; 40 g+ distance lures rarely needed

Run your fingers along the leader after every few casts to feel for damage.

Minagiman’s take

Proper surf fishing reachable by train from the Tokyo area is rare. Seisho is the surf where you do not need to cast far — but steep means dangerous. Bring two rules with you: no long casts needed, and no wading.