Detail of Phraya Boran Rachathanin's map - Anno 1926
Text & maps by Tricky Vandenberg - April 2013
Khlong Tho (also called Khlong Pak Tho) is a still existent canal situated on
Ayutthaya's city island, west of the
Grand Palace. The canal was a shortcut in the
oxbow of the old
Lopburi River. It has today its origin at Khlong Mueang opposite Wat
Choeng Tha and its mouth at the Chao Phraya River in front of Wat Phutthai Sawan. In
its southern stretch, the canal is called Khlong Chakrai Yai, identical to the defunct
Khao Pluak Canal, which extension is called Pratu Jin Canal. [1]

It is one of the three large canals running north to south of which two still are in existence.

Five bridges crossed Khlong Tho - Chakrai Yai. [2] The first bridge called
or Gold Bridge crossed the Tho Canal right below its confluence with the
Lopburi River and led into the palace grounds near the Khuha Chong Lom Gate (1).
This bridge stood likely in the area where today U-Thong Rd crosses Khlong Tho just
below the Khlong Tho Water Regulator.

A second brick bridge called the
Saphan Sai So or Chain Bridge crossed the canal in
front of the Maha Phokharat Gate of the Grand Palace. A third bridge called
Lam Hoei or Wry Waterway Bridge connected the road coming from the Rear Palace
called Thanon Lao or Lao Street with Thanon Talaeng Kaeng or the "Street of the

A fourth bridge called
Saphan Nang Hong or Lady Swan Bridge connected Wat
Khwit Road (2) with
Wat Kuti Salak. The fifth and last bridge over Khlong Tho was the
Khun Lok Bridge north of the Chakrai Yai Water Gate. Sujit Wongthet
indicates it just opposite
Wat Jao Phram on one of his maps.

Both entry and mouth of the canal had water gates (3) respectively the
Pratu Pak
Khlong Tho
and the Pratu Chakrai Yai water gates. These water gates have been
replaced by modern water regulators since the severe flooding of Ayutthaya in 1995.
The regulators were of no avail during the flood of 2011.

The ponds of the Grand Palace were fed by the waters of the Tho Canal. For this
purpose there were two palace water gates. The
Udom Khongkharat Gate referring
to Mae Khongkha, the Goddess of Water, filled the moat around the
Ratanat Maha Prasat
. Another water gate called the Cholachat Thawara Sakhon
regulated the outflow from the Crystal Pond inside the royal palace. (4)

On the east bank of the canal along the western wall of the palace there were two
fortresses being
Pom Thai Sanam (also called Pak Tho Fortress at the entry of the
canal) and
Pom Suan Angun (at the end of the Crystal Pond at the Grape Garden
corner) being part of the palace defenses. There was no fortress at the mouth of Khlong
Chakrai Yai opposite Wat Phutthai Sawan (5).

From Khlong Tho there were a number of smaller canals departing. On the east side the
most important side canals were
Khlong Nakhon Ban and Khlong Pa Mo; on the west
Khlong Fang, Khlong Chang Maha Chai and Khlong Klaep.

It is not known were exactly Khlong Tho ends and Khlong Chakrai Yai begins and its
denomination is likely depending of who is living in what part. For the ease I will end
Khlong Tho at Saphan Lam Hoei. Most of the points of interest along the canal with
exception of the Grand Palace were along the Chakrai Yai section, so I will cite them


(1) This gate could not be determined on the Grand Palace area.
(2) The road must have been called after a temple in the vicinity. Until today I could not
find any trace of a Wat Khwit on the old maps of Ayutthaya.
(3) Two of the eleven water gates around Ayutthaya city island.
(4) There is discussion whether this gate regulated the outflow of the moat around the
Banyong Ratanat Maha Prasat or the outflow of the Crystal Pond in the Grape Garden.
(5) Here also is discussion whether the Suan Angun Fortress stood in the NW or the
SW corner of the Grape Garden.


[1] Tamnan Krung Kao.
[2] Geographical description of Ayutthaya: Documents from the palace - Dr Winai
Pongsripian - Bangkok (2007) - page 35-6.
Khlong Tho on Kaempfer's map
Bellin's 1750 map
Detail of Phraya Boran Rachathanin's map - Anno 1926
(Detail of Phraya Boran Rachathanin's map - Anno
(Bellin's 1750 map)
(Khlong Tho on Kaempfer's map)