There are two ways one could build an Eiruv on an island:

  1. One build walls, Tzuras Hapesachs, etc.
  2. One relies on the "natural" walls. This hetter applies only if
    1. The ocean does not bring up sediment.
    2. One could see the whole island in one shot from one location (which is 15 mil).

If one build real walls, they can be as big as one wants as long there are no farms bigger than a beis-saasaim.

Some poskim say there are real walls around Manhattan. If so, why is the Manhattan Eiruv not around the whole Manhattan?

Moreover, why do some poskim still bring up the issue of "The ocean does not bring up sediment"?

  • 1
    can you elaborate a little on "the ocean does not bring up sediment"? What are the halachic ramifications if it does or doesn't? Why shouldn't they still bring it up?
    – Menachem
    Sep 16, 2011 at 8:43
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    Rabbi Yosef Gavriel Bechhofer wrote the book on the modern metropolitan eruv. amazon.com/Contemporary-Eruv-Eruvin-Modern-Metropolitan/dp/… Here is a link to the book (I think) available online: aishdas.org/rygb/eruvp1.htm . Here is a link to a shiur he gave on the subject. rygb.blogspot.com/2011/02/… . I haven't read or listened to these, but they may answer your question. - here is a two part shiur on the same subject: torahlectures.com/s-Rabbi-Yosef-Bechhofer.aspx
    – Menachem
    Sep 21, 2011 at 22:49
  • The original Manhattan Eruv did go around the whole island, if I recall correctly. It was controversial. At one point, people built a "West Side Eruv" for just the Upper West Side of Manhattan; in June 2005 local rabbis decided that the structural changes in the sea walls and piers rendered the old eruv invalid (estherkustanowitz.typepad.com/myurbankvetch2005/2005/07/…). In 2004 the West Side eruv had been expanded to the East Side; it's since been expanded downtown.
    – JXG
    Nov 8, 2011 at 13:09
  • Great article. I'm on Norfolk Island which is 5 by 3 miles. Mainly high cliffs, and can all be seen from the small mountain. Good to know I can carry if I need to.
    – user6936
    Aug 28, 2014 at 10:27
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    Yehoshua, please note that Mi Yodeya is not an authoritative source of rabbinic rulings. I encourage you to speak with your rabbi before acting on anything you read here. Welcome to Mi Yodeya! I hope you'll look around and find other material of interest, perhaps starting with our shabbat collection.
    – Isaac Moses
    Aug 28, 2014 at 13:05

1 Answer 1


A wall must drop/have a slope down of 10 tefachim within 4 amot to be a wall. For example, a seashore may take a large distance until you are standing at a point 10 tefachim lower. A table or pier will be a very short space to drop (at least) 10 tefachim.

If the entire coast of Manhattan fits this criterion then it would be a wall. The Manhattan eruv is under the rabbis who give it its kashrut/maintenance. If other rabbis hold that Manhattan has walls and they don't, then this eruv won't extend for the whole island.

There are 2 general factors in Eruv. 1) Is it a good structure/good walls etc? 2) Is the area inside an eruv an area that can have an area around it? I.e., if you put an eruv around a reshut harabim it doesn't do anything — still can't carry.

If you can prove that Manhattan has halachic walls then it could well be point 2 that stops Manhattan having an eruv under those rabbis. A rabbi that was involved in the Manhattan eruv told me that even the (smaller) Manhattan eruv may have problem 2.

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