There are four basic food groups: milk chocolate, dark chocolate, white chocolate and chocolate truffles.

You therefore can count on a square meal (of the chocolate box sort) when the fourth annual Chocolate Festival opens tonight, October 5, with a preview party at Featherstone Center for the Arts on Barnes Road in Oak Bluffs.

On Saturday, Oct. 6, everyone is invited to join the fourth annual Justin Coleman Memorial Hike-a-thon. The 10-mile hike begins at the Coleman’s house on 150 South Road in Chilmark. This year, the hike also will be in memory of Alex Cohen, a friend of Justin’s who died in an automobile accident driving from Martha’s Vineyard to Duke University at the age of 19.

M.J. Bindu Delekta’s sacred Circle of Yoga studio in Vineyard Haven begins its fall season with free classes.

Chair yoga, which uses the support of a chair and stretches the entire body, is appropriate for seniors and anyone with physical limitations. This class will meet on Monday, Oct. 8 at 9 a.m.

Yoga on the Ball combines the wisdom of yoga with the support and core-building of the exercise ball. This class meets on Tuesday, Oct. 9 at 5:30 p.m.

For details, call 508-696-4513 or see online sacredcircleofyoga.com.

New Hampshire advertising agency executive David Flood has produced a documentary on Vineyard life and the Martha’s Vineyard Striped Bass and Bluefish Derby.

The hour-long color film, Feeding the Water, will premiere today at 7 p.m. on MVTV and will run on the station through the remainder of the derby. Mr. Flood filmed for five weeks during the 2006 derby.

Alison Shaw Gallery is opening up again for a Columbus Day weekend sale. On Saturday and Sunday from 2 to 5 p.m. posters are 15 per cent off, cards are one-third off, selected prints are 25 per cent or more off regular prices.

After this weekend, the gallery will be available only by appointment, so visit this weekend at 88 Dukes County avenue in the Oak Bluffs Arts District. For details, call 508-696-SHAW or see Alisonshaw.com.