ON MONDAY, the Shannon-Erne Waterway re-opens in Ireland. It links Carrick- on-Shannon with Lough Erne in the north of the republic, via 16 locks. To coincide with this event, Euromapping has published a map of Irish waterways. It shows more than 600 miles of navigable rivers and canals for cruising. Even landlubbers may find the chart intriguing: whatever happened, for example, to Kilkenny Canal? (It was never completed.) The map costs pounds 6.50 from the Inland Waterways Association, 114 Regent's Park Rd, London NW1 8UG.